Automotive Work

People who know me personally,  know about my rather-extreme vocalizations while I am working on cars and pickup trucks.  This first started many decades ago,  when I was doing all my own maintenance and repair to various air-cooled VW vehicles. 

It has gotten more vocal since.  The more modern vehicles have just made the effect worse,  because they are so damned hard to work on (too much crap piled into too little space),  and they have proven far less reliable in so many multiple ways. 

I have spent the last 3 years working in a repair shop (after coming out of retirement to do that for two friends) on all sorts of cars and trucks.  Whatever walks in the door.  What I have seen is two-fold.  I have now gone back into retirement in the summer of 2022.  And,  I do not want to come back out!

First:

Of the widely-available vehicles,  I have not seen very many Toyotas or Subarus in the shop.  I have seen a lot of Fords,  Chevys,  Dodges,  and Jeeps.  I have also seen quite a few Nissans,  Hondas,  and Hyundais.  If you are interested in reliability and low maintenance costs,  then Toyotas and Subarus are the cars to look at.  Period.  End of issue.  Volvos,  etc.,  don’t count,  there are so few of them out there. 

Second:

Of the ones I have seen more often in the shop,  generally speaking,  the later models after about 2005 are the ones which are noticeably less reliable.  This takes the form of computer and sensor failures,  not so much mechanical failures like brakes and wheel bearings,  transmissions,  or engine failures!  The late-model sophisticated electronics are just not as reliable as the mechanical components,  and that’s a fact,  Jack! 

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In point of fact,  you can no longer splice wires back together after a rat or squirrel has chewed them,  because the idiot computer cannot accept the change in wire resistance,  after you splice it!  That is totally ridiculous!  But true!  And quite expensive.   You have to replace the wiring harness.

And the manufacturers are making mistakes that they simply should not be making!  One example (of many) is the 2-piece spark plug that Ford introduced for a while in the late 1990’s and early 2000’s.  Why change something which has worked for over a century?  Ridiculous!  And very expensive to repair,  because it breaks apart when you try to remove the plug,  and it takes a special tool to get the broken stub out,  without enough room to work.

The Trend Toward Everything Computerized Is Bad

I am totally against this!  The term “artificial intelligence” (AI) is an oxymoron,  as far as I am concerned!  No computer is yet capable of responding to anything it has not been programmed for!  And the programmers simply do not know all the things the system must cope with.  And that’s another fact,  Jack! 

If the programmer did not anticipate something (and they so often do fail to anticipate common problems),  then people die in the real world,  as Tesla is learning so very reluctantly!  It’s utter bullshit to think otherwise!  Tesla is not alone in this mistake!  But they really have made this mistake!  It’s why they keep getting into trouble with the feds.

Don’t get me wrong:  Teslas are good cars!  Just do NOT use the auto-pilot feature!  It will get you killed,  sooner or later!

It's one thing to have a computer navigate for you.  I personally find that to be a serious driver failing,  but most folks today do not.  I like paper maps, myself.  But so be it.  It is quite another thing to have a computer drive your car for you,  while you dope off or nap.   That is what a computer cannot do,  unless and until it has been programmed for every possible contingency.  My contention is that we are still very,  very far from that!  That much is being proven by the current accident rates. 

There is (and has been for many decades) a garbage-in,  garbage-out law (GIGO law) relating to computers.  Computers quite happily process bad inputs,  and spit out the corresponding bad results data,  without any notation that they are processing bad input data.  That’s a very serious failing. 

You the human must be able to sort out the garbage output from the computer,  from the “good stuff” that is actually correct.  The only way to do that in a car is to drive the car yourself.  The current reliance on computer controls denies that unpleasant little fact of life.  And it is killing people!  So,  do not trust the computer!

I Recommend:

Dare trust nothing!  Learn to drive your car as if there were no automatic functions.  Do not trust any of the automatic functions,  except the automatic navigation functions.  Otherwise,  just do it for yourself.   

As for navigation,  look on the internet before you depart.  You may find the automatic navigation function is in some degree of error.  I usually find it delayed to the point of uselessness in real-time navigation,  myself.  Such as telling you to turn,  after you have already gone through the intersection. 

Warnings of exit and entrance ramps are too often delayed past the point of useful navigation.  You really have to be able to zoom in close on an internet map to see these things,  and once you are driving,  that is too late!

Do not buy a highly-automated car.  It’s just that simple.  Learn how to do it for yourself.  You will live longer.

 

Understanding Your Tires

There are basically four types of tires seen on passenger cars and light trucks (pickup trucks).  These are the P-metric and ISO-metric tires most often seen on passenger cars,  and the LT-metric and “flotation” (not metric) tires seen on light trucks.  In some cases,  light trucks come factory-equipped with P-metric or ISO-metric tires,  but you do not see light truck tires as factory equipment on passenger cars.

P-metric is a US Tire and Rim Association (TRA) designation system with tire section width specified in metric millimeters,  but rim size specified in US customary inches.  Section height is given as a percentage to be applied to section width.  It will have a “P-“ in front of the numbers that specify sizes.  This size code is molded into the tire sidewall.  There is a specific set of load-inflation tables from the US TRA that go with these tires (and no others).

ISO metric uses exactly the same numbers to specify size,  but lacks the “P-“ in front of the numbers that are molded into the sidewall of the tire.  Section width is given in millimeters,  and rim size in inches.  Section height is given as a percentage to be applied to section width.  There is a different set of load-inflation tables to use with these tires,  from the European Tyre and Rim Technical Organization (ETRTO).

LT-metric refers to a US TRA class of light truck tires,  using the same metric section width,  section height percentage,  and rim size numbers,  as the P-metric and ISO metric tires.  Those numbers are preceded by “LT-“.  These LT-metric tires have their own set of load-inflation tables from the US TRA.

The “flotation” sizes are the final form of the old US customary inch-size designations.  These are inch measurements for overall diameter,  section width,  and rim diameter.  For the light truck application,  this size designation is followed by the letters “LT”,  as well as another letter designating the load range of the tire. These have their own load-inflation tables from the US TRA.

You must use the correct load-inflation table for the type of tires installed on your car.  These tables are downloadable off the internet.  See the section Load Inflation Tables below.

What Is On the Sidewall

Using the spare for one of my own passenger cars as the example,  here is how to read the pertinent information off the sidewalls of the tire.  The example is an ISO metric tire manufactured by Firestone at a factory in Brazil.  The basic tire size and application information is shown in Figure 1.  The same information is molded into both sidewalls (inner and outer).  Right under the brand name logo,  the code shown reads “175/65R14 82S M+S”.  There is no “P” and no “LT”,  so you know it is ISO-metric.

The tire section width is 175 mm from inner to outer sidewall (not the tread width,  but from bulge to bulge of the sidewalls).  The ratio of section height to section width is 65%,  meaning the section height is 0.65 * 175 mm = 113.75 ~ 114 mm.  Section height measures from where the bead seats down inside the rim edges,  out to the outer tire diameter.  The “R” indicates radial construction.  A “D” or a “B” indicates the now much-rarer bias-ply construction.  The rim diameter is 14 inches,  which is also measured down inside the rim edges,  where the tire bead seats. 

The “82S” tells you the service the tire is meant for.  The load index is 82;  higher index is heavier load capability,  but this varies from size to size,  so you have to use the load-inflation tables.  The speed rating is “S” (112 mph).  The “M+S” is “motor plus sport”,  which is advertising hype,  not really useful.

Figure 1 – Basic Tire Type and Size Information

Somewhere on the sidewalls will be a block of information that gives you the max load and max inflation values the tire is rated for.  Values are given in both metric and US customary units for both items,  as shown in Figure 2.  For this example,  the max load the tire can carry is given as 475 kg = 1047 lb,  and the max inflation is given as 300 KPa = 44 psi.  The max inflation would be “gauge” pressure above local atmospheric,  not absolute pressure.  Max inflation is driven by how the tire is constructed,  not necessarily by the max load it carries in the rating tests.   More below about that.

It is crucial to understand that these max load and max inflation pressure ratings do not necessarily go together (although they can),  nor are they the recommended inflations for any given car.  But,  combined with the data in the appropriate load-inflation table,  together they give you a very clear picture of what loads the tire can safely carry,  and what pressures are required to achieve that capability. If the tires are stock size for the car,  just use the inflation pressures listed on the car’s placard.  If not,  you must adjust inflations using either the max axle loads and the load-inflation table for the replacement tires,  or the load-inflation tables for both the stock and the replacement tires.

Somewhere else on the sidewalls will be molded the relative ratings for treadwear,  traction,  and temperature.  These are shown in Figures 3,  4,  and 5 for this example,  as treadwear “400” (Fig. 3),  traction “A” (Fig. 4),  and temperature “B” (Fig. 5).  These are less informative than often believed.

The treadwear rating is relative to what a cheap tire might provide under the same loading and service conditions.  Values seen are “100” (the cheap-tire reference),  “200”,  “300”,  and “400”.  The higher values are supposed to provide more miles of tread life before they are worn out.  However,  the “400” does NOT last 4 times longer than the “100”;  it only lasts a little longer,  most of the time!  The changes in tire composition (usually extra carbon in the rubber) that confer longer tread life also act to lower traction and perhaps temperature ratings. The higher the carbon loading,  the harder the rubber.

Traction ratings are “A”,  “B”,  and “C”,  with “A” representing the best.  I’ve never seen a “C” traction tire,  and I cannot tell much difference between an “A”-rated tire and a “B”-rated tire.   I don’t see very many “B”-rated tires,  anyway.  Harder tires at higher carbon loading break free and skid easier.

Temperature ratings are also “A”,  “B”,  and “C”.  “A” is the best,  but I have never actually seen anything but a “B” rating ( I do not use retreads).  Tires run hotter under heavy load,  especially in hot weather.  If they get too hot,  the risks of tread separation and blowout rise greatly!  Retreads really suffer from this,  as the vulcanization temperature for the bond joint of the new tread cap onto the old tire,  is necessarily lower than the vulcanization temperature for the old tire carcass.  Otherwise,  the tire would fail during the retread operation.  It is an ugly little fact of life that rubber heated above its vulcanization temperature re-liquifies.

The other thing you really need to know is how old the tire is.  That is because tire rubber degrades over long periods of time,  leading to the tire blowing out,  or otherwise coming apart catastrophically.  A lot of people call this “dry rot”,  but it is really the action over time of ultraviolet light,  plus ozone and other chemicals in the air,  degrading the rubber. 

Somewhere on the outer or inner sidewall,  but not necessarily both,  is a DOT code that will tell you when the tire was manufactured.  For the example,  I first looked at the outer sidewall and found “DOT E2EX 38B” plus a blank oval where the date code should be.  That is shown in Figure 6.  Then I looked at the inner sidewall and found “DOT E2EX 38B 3110”.  The date code is the “3110”. That is Figure 7.  

Figure 2 – Max Load and Inflation Ratings

Figure 3 – Treadwear Rating (“400” Shown)

Figure 4 --  Traction Rating (“A” Shown)

Figure 5 – Temperature Rating (“B” Shown)

Figure 6 – DOT Code Date Is Missing On Outer Sidewall (Empty Third Oval)

Figure 7 – DOT Code Date Is Present On Inner Sidewall Third Oval (Date Code 3110)

This 3110 date code means the tire was manufactured in the 31^st week of calendar year 2010.  This is currently late 2021,  so this tire was manufactured 11 years ago,  and has been in storage waiting to be sold,  ever since then.  As long as the storage was relatively cool,  and especially dark,  the long storage time should not matter that much.  But there is no avoiding the exposure to ozone in the air.

Unfortunately,  there are no hard-and-fast rules for how old a tire can be.  A sort-of general rule of thumb is that it should not exceed 6 to 10 years old,  in service on the car.  Storage doesn’t count much against that,  except for the ozone damage,  as long as it was stored inside and dark.  Myself,  if I haven’t worn this tire out in 5 to 6 years,  I will consider replacing it as “unreliable in service” due to age.

Tire Speed Ratings

The published speed range ratings look like the following table.  As a general rule,  do not exceed the speed rating for the tires you have,  even for a short transient.  If the weather is hot or the load is high,  stay well below the rated top speed.  What happens is that the tire rapidly gets too hot flexing as it rolls,  while simultaneously being stressed harshly by centrifugal forces.  This effect gets greatly exaggerated at high loads or in hotter weather,  and failure can happen in minutes,  or even seconds. 

TIRE SPEED RATINGS TABLE

Tire Speed Ratings  from https://www.readingbody.com/understanding-truck-tires-load-ratings-and-sizes/ as of 8-25-2021

·        L: Only apply these tires to off-road trucks that will not exceed 75 mph.

·        M: Use with temporary spare tires at no faster than 81 mph.

·        N: These tires have a maximum speed of 87 mph.

·        P: Tires with a P rating, cannot go faster than 93 mph.

·        Q: Q tires are usually winter studded or studless tires and should not exceed 99 mph.

·        R: For heavy-duty LT trucks, the rating may be R, which indicates a speed limit of 106 mph.

·        S: Family vans and sedans use the rating of S to indicate speed maximums of 112 mph.

·        T: Family sedans and vans may also use T-rated tires, which can drive up to 116 mph.

·        U: U tires can reach 124 mph.

·        H: Sports vehicles with H speed ratings can hit 130 mph.

·        V: Sports cars, sedans and coupes often use V-rated tires, which have speed ratings up to 149 mph.

·        W: Exotic sports cars use tires that can reach speeds up to 168 mph and have a W designation.

·        Y: The fastest speed rating — once Z which indicates faster than 149 mph — now is Y, which allows the tires to reach 186 mph.

For the example,  the speed rating is “S”,  corresponding to 112 mph on a passenger car.  That particular car (a 1998 Nissan Sentra) will not go that fast on level ground anyway,  so this isn’t much of an issue.  It won’t even go that fast downhill,  under most circumstances.  It’s a little 1.6-liter 4-cylinder!

Load-Inflation Tables

I got my copy of the four load-inflation tables as one document from the Toyo tire website:  https://www.toyotires.com/tires-101/tire-load-and-inflation-tables

On that website,  there is a link to the stored tables,  which can be downloaded as one single file in pdf format.  That link looks like:  Load & Inflation Table Application Guide

I recommend that you visit the indicated site,  follow the indicated link,  and download the pdf document that contains the four load-inflation tables all in one place.  That file also contains instructions for exactly how to use them.  These four tables cover P-metric,  ISO metric,  LT-metric,  and “flotation” tire types. 

There is an oddity to be aware of,  for dealing with LT-metric light truck tires.  The load index is often two numbers separated by a slash,  not just one.  The higher number pertains when there is a single tire and rim on the end of the axle.  The lower number pertains when there are two tires on two rims on the end of the axle.  The lower load index number represents a lower max load to be carried by each tire. 

The reasoning behind this is what the remaining tire can carry,  if one of the two on the end of the axle deflates.  The remaining inflated tire has to carry the load of the pair,  until the event is detected and the vehicle can be stopped for repair.  It can carry some overload,  but not a full factor 2 overload,  for a short time.  So,  the load index rating is reduced for that dual installation and deflation scenario.

There is another oddity to be aware of,  if P-metric passenger tires are fitted to a light truck.  Light truck-rated tires (the LT-metric,  and “floatation” with “LT” in the size) are typically built of tougher construction,  to withstand more routine abuse and more destructive driving conditions.  P-metric passenger car tires are just not built to withstand that kind of abuse.  While ISO-metric tires are generally a little tougher than P-metric tires of the same size,  they also still fall short of truck service. 

That is why the US Federal Motor Vehicle Safety Standards (FMVSS) demand that the allowable load ratings at any given inflation value be reduced by a factor of 1.10,  if a P-metric tire is to be fitted to a light truck.  If the factory tire on a light truck is a P-metric tire,  this factor 1.10 reduction has already been applied at the factory.  This load rating reduction of the ISO-metric tires is not so required,  but something like that would be highly recommended. 

Resizing Loads and Inflation for the 1998 Nissan Sentra

This is an odd case,  as the stock load margins are very low,  and this car has a history of hot-weather tire blowouts.  P-metric tires of this size (P-175/65R14 load index 81) are no longer so common;  instead the slightly-higher load index ISO metric tires (175/65R14,  load index 82) are now more common. 

The tire inflation placard for this vehicle (for the P175/65R14 size) lists 33 psi front,  29 psi rear for inflation.  The placard weight ratings are GAWR (gross axle weight rating) 1872 lb front (where the engine is),  and 1567 lb rear,  with a gross vehicle weight rating (GVWR) of 3413 lb,  which is always a little less than the sum of the front and rear axle ratings. 

Half the axle ratings are 936 lb front,  and 783.5 lb rear,  which the tires must bear during straight constant-speed driving on level ground.  At the placard inflations,  the tire load capabilities minus the axle rating loads (load margins) are rather small numbers: only about 58 lb front and 153.5 lb rear.  The plot is in Figure 8.  Note that the max load capability of 1019 lb is at the max inflation 35 psig.  

Increasing the rear inflation level to 30 psig raises that load margin to about 168.2 lb.  Increasing the front inflation to 34 psig raises the front load margin to about 74.7 lb.  These slightly higher load margins should help reduce the blowouts,  while still maintaining a handling difference of 4 psi,  same as stock.

Figure 8 – Tire Loads and Capabilities for P-Metric Tires on Nissan

The ISO-metric tires have a higher max inflation pressure (44 psig) than the pressure at max load (36 psig).  One plots this as constant load from the test data max load point,  up to the max inflation pressure point,  as shown in Figure 9.  If we choose 36 psig front and 32 psig rear,  we have larger load margins of 111 lb front and 164.5 lb rear,  at a front-to-rear handling differential of 4 psi,  same as stock.  

Figure 9 – Tire Loads and Capabilities for ISO Metric Tires on Nissan

Accordingly,  I am recommending revised tire inflation levels of 34 psi front and 30 psi rear,  vs the factory placard levels of 33 front and 29 rear,  whenever P-metric tires are used.  I also recommend the slightly-higher-still levels of 36 psi front and 32 psi rear whenever ISO-metric tires are installed.  There is no change to the 60 psi inflation for the “doughnut” spare. 

What this recommendation does is provide tire load capacities equaling or exceeding factory stock levels,  while preserving the front-to-rear inflation differentials.  That outcome is in accord with the guidelines for using the load-inflation tables.  The difference is that my procedure gets you the actual load margins for both the original stock and the revised tire selections.  You have more information.

Resizing Loads and Inflation for a 2005 Ford Focus

This vehicle came factory stock with P195/60R15 standard load (SL) tires of load index 87.  The stock tire inflation placard recommends 32 psig inflation all around,  no differential front-to-rear.  Stock tire load margins based on the load-inflation plot of Figure 10 are 158.5 lb front and 273.5 lb rear.  Hot weather blowouts were never a problem with this car.  There is no need to change the stock tire specification. 

Figure 10 – Tire Loads and Capabilities for P-Metric Tires on Ford Focus

Those factory stock tires are now hard to find,  but the ISO-metric equivalent size is available.  Those are 195/60R15 standard load (SL) tires of load index 91 and speed rating H (130 mph).   These tires are constructed stronger,  reflected in the larger load index,  and have a max inflation of 51 psig,  versus the stock P-metric tire max inflation of 35 psig.  

One would expect higher load capacities at pretty much any pressure,  and this is borne out in the load-inflation plot of Figure 11.  Those data lead to substantially-larger load margins of 236.5 lb front and 351.5 lb rear at the same 32 psig inflation.  These tires will be “tougher” against abuse at the same inflation,  than were the factory-stock P-metric tires. 

The recommendation is keep the factory stock 32 psig inflation (front and rear),  whether the tires are P-metric or ISO-metric.  The 60 psig “doughnut” spare is no different than it was.

Figure 11 – Tire Loads and Capabilities for ISO Metric Tires on Ford Focus

Resizing Loads and Inflation for a 2010 Toyota Prius

This vehicle came factory stock with P-metric P195/65R15 standard load (SL) tires of load index 89,  placarded for inflation at 35 psi front and 33 psi rear.  A plot of the load-inflation data in Figure 12 reveals the rather substantial load margins to be 144 lb front and 176.5 lb rear.  

Figure 12 – Tire Loads and Capabilities for P-Metric Tires on Toyota Prius

The replacement tires are now ISO-metric 195/65R15 standard load (SL) tires of load index 91 and speed rating H (130 mph).  The corresponding load-inflation data plot is given as Figure 13.  These tires increase the load margins to 177 lb front and 185.5 lb rear,  at the same inflation levels. 

Figure 13 – Tire Loads and Capabilities for ISO Metric Tires on Toyota Prius

Thus,  the recommended tire inflation levels need not be revised from the placarded 35 psig front and 33 psig rear.  The 60 psig “doughnut” spare is unchanged.

Resizing Loads and Inflation for a 1995 Ford F-150

This is another very odd case.  The original factory stock P-metric tires are now unavailable for this rather old pickup truck.  These were P235/75R15 extra load (XL) tires of load index 108.  The load-inflation plot for them is given in Figure 14.  Note the application of the 1.10 derate factor leading to the orange derated curve below the blue stock rating curve.  That derate factor is per the FMVSS for using P-metric tires on a light truck.   

Figure 14 – Tire Loads and Capabilities for Factory Stock P235/75R15 XL Tires

The front load margin calculates as 406.1 lb at 35 psig inflation,  and the rear load margin as only 84.5 lb at 41 psig inflation.  Max inflation for these tires is 50 psig.  That loading would be pretty much in accord with 6 occupants in the cab and the full rated 1000 lb of cargo in the bed of the truck. 

I could not get those tires recently.  LT-metric tires were available in this size,  but only with the block tread pattern that does not wear properly with the twin I-beam suspension this truck has.  The only P-metric tires I could find were slightly lower section height,  and (more importantly) only standard load (SL)!  Those were P-235/70R15 SL tires of load index 102.  The load-inflation table data for those tires are plotted in Figure 15 as the blue curve,  and then derated by a factor of 1.10 per the FMVSS as the orange curve.  Max load for these tires is at 35 psig,  and max inflation is 44 psig. 

Figure 15 – Tire Loads and Capabilities for P235/70R15 SL Replacement Tires

With these tires,  which are currently on the truck,  the front load margin at the placard 35 psig inflation is reduced from 406.1 lb down to 206.1 lb.  Technically,  that reduction violates the tire sizing guidelines given in the load-inflation tables document,  but it is still a fairly substantial positive margin. 

The rear load margin at the placard inflation of 41 psig falls from 84.5 lb to a -176.4 lb shortfall,  and THAT is a serious problem indeed!    A small positive load margin would obtain if the rear wheel load were reduced by about 200 lb at each wheel.  That corresponds to a 400 lb reduction in the rear axle load,  in turn corresponding to a 400 lb reduction in the truck bed load. 

The reduced section height also leads to a 3.2% reduction in outer diameter,  making the speedometer reading another 2 mph high at a real 60 mph on the radar,  for that reason alone. 

I have chosen to drive the truck this way at 35 psig front,  41 psig rear (whenever loaded),  but to reduce the truck bed payload from 1000 lb to 600 lb,  and to slow down to about 50 mph whenever 600 lb is exceeded.  This is primarily because they are SL,  not XL,  tires!  But I do not have to like this situation! 

I do not know if a better tire selection is really available,  but I did identify one represented in the load-inflation tables:  P245/70R15 XL tires of load index 108.  These would have a section width 10 mm (0.4 inch) wider,  but they fit the same stock rims.  The outer diameter is much closer to stock.  See Fig. 16.

Figure 16 – Tire Loads and Capabilities for P245/75R15 XL Candidate Replacement Tires

These tires,  if available,  would more-or-less restore the former load margins.  At 35 psig,  front load margin becomes 406.1 lb (same as stock).  At 41 psig,  the rear margin becomes 94.5 lb,  very slightly better than stock.  The only risk would be rubbing something in the front wheel wells during sharp turns,  because of the wider section width. 

The availability of LT-metric tires is far better,  in the stock size.  The problem is the block tread pattern wearing improperly,  something I have already experienced!  It really is a serious problem.  Assuming I could find non-block tread patterns in an LT-metric tire,  the only question is which load range (and the corresponding inflation levels) is appropriate.  Fig. 17 is for LT235/75R15 Load Range C tires.  No derate factor is required.  The load index is 104,  lower than stock.

Figure 17 – Tire Loads and Capabilities for LT235/75R15 Load Range C Tires

These tires require different inflations to meet the load margin needs.  At 45 psig,  the front load margin is near stock at 387.5 lb,  and at 50 psig,  the rear load margin is near stock at 85 lb.  This is acceptable,  but we are running the rear tires right at their max inflation limits.   That is not such a good idea!

Similar data for LT235/75R15 Load Range D tires are given in Figure 18.  The load index is 110,  higher than stock.  At front 45 psig,  we get the same 387.5 lb load margin as the load range C tires.  At 60 psig rear,  we get a greatly-improved load margin of 335 lb.  And,  we are still under the max inflation rating of 65 psig!  These would be quite acceptable,  if the non-block tread pattern could be obtained. 

Figure 18 – Tire Loads and Capabilities for LT235/75R15 Load Range D Tires

The LT235/75R15 Load Range E tires are plotted in Figure 19.  These have load index 116 (much better than stock),  and a max inflation of 80 psig.  

Figure 19 – Tire Loads and Capabilities for LT235/75R15 Load Range E Tires

At the same 45 psig front,  load margin is the same 387.5 lb as the load range C and D tires.  At the same 60 psi rear as load range D,  the load margin is the same 335 lb as the load range D tires.  These meet requirements,  but have excess capability (and expense) that are not needed.

The recommendation here depends upon the tread patterns available in this size for LT-metric tires.  If the non-block tread pattern is available,  then LT235/75R15 XL Load Range D tires of load index 110 are greatly preferred,  to be inflated 45 psig front,  and 60 psig rear,  when loaded.  Unloaded,  one can use 45 psig rear,  and it won’t break away so easily on a wet road.

Failing the availability of the non-block tread pattern,  we would prefer the original stock P235/75R15 XL tire of load index 104,  or as a backup possibility,  could accept the P245/70R15 XL tire of load index 105,  at 35 psig front,  and 41 psig rear when loaded.  35 psig rear unloaded handles better in the rain. 

Under NO circumstances,  should a standard load tire ever again be accepted for this truck!

Final Remarks

Those of you readers who are interested in refitting with larger diameter rims and lower section height tires,  you need to follow pretty much the same the same procedure as I did. 

Here is the procedure:

Go locate a copy of the load inflation tables for the four tire classes.  Look through them to determine where the data tables for each type really are.  Get familiar with them.

Find and plot the proper load-inflation data for your tires,  just like I did.  It will be a slanted straight line up to some max load point,  then a horizontal line from that max load point,  up to the max inflation pressure (if different).  Some tires have max load at max inflation,  most do not.

If you are looking at using passenger car tires on a light truck,  always divide the tire load values from the table by 1.10,  and plot them reduced that way (don’t mess with the inflation pressures).  Use those derated load data for your analysis.  You need not do that with LT-metric or “flotation” size tires rated “LT” for light truck application.  The FMVSS demand this derating for P-metric;  I’d highly recommend it for ISO metric,  too.

Look up or otherwise find your front and rear gross axle weight ratings.  Divide those numbers by 2 to represent the max loads applied to the wheels at the ends of the axles. 

For the stock configuration at the stock tire inflations,  compute for the front and rear the tire load capability minus the wheel load applied.  Those are your stock load capability margins,  front and rear. 

For your new configuration,  do the same thing for a number of candidate inflation pressures.  You are trying to equal or exceed the stock tire load margins front and rear,  at inflation pressures in the new tire that are (1) less than its max inflation,  and (2) that differs front-to-rear by no more than a psi or so,  from the stock difference front-to-rear.  Maintaining that front-to-rear difference is driven by handling effects:  it really is important,  especially in passenger cars.      

Lists of Some Articles By Topic Area

Search code 21102021

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Update 8-2-2026:     added multiple articles to multiple topics below. 

Update 2-10-2026:  added several to multiple topics below.

Update 6-10-2025:  added several to multiple topic areas below.

Update 4-10-2025:  added several to multiple categories below.

Update 4-7-2024:  added 3 to rocket,  below.

Update 3-6-2024:   added 3 to rocket,  below. 

Update 2-13-2024:  added 1 to ramjet and 6 to rocket, etc. below.

Update 10-1-2023:  added "Basic Thermal Results for High Speeds" to 2 topics below.

Update 9-2-2023:  added "Purported SR-72 Propulsion" to 3 topics below. 

Update 7-18-2023: added 1 article to forensics.  

Update 6-21-2023:  added 2 articles to rocket ballistics and vehicle performance list.

Update 5-4-2023: added 1 article each to aerothermo and forensics lists.

Update 2-4-23:  added new nozzles article to aerothermo and ballistics lists.

Update 1-1-23:  added catalog topic for towed decoys,  this text color.

Update 12-2-2022:  two ramjet articles added to that topic list,  this color.

Update 9-5-2022:  some recent articles added to the lists,  this text color.

Update 10-1-2022:  some others added,  this color.

Update 10-30-2022:  a couple added,  this color.

------------------------------

I was once an all-around ramjet design,  development,  and test engineer,  among many other things,  including rocket work.  This was mostly at a plant in McGregor,  Texas,  once known as Rocketdyne or Hercules.  Part of that reservation is where SpaceX tests rockets now. 

I did just about everything there was to do,  for this ramjet work.  There are very few indeed with knowledge and experience this comprehensive,  I was definitely not a narrow specialist!  But my knowledge and abilities,  in each of all these different specialty disciplines,  was actually quite substantial and deep!  

My design analyses usually took the form of custom hand-calculations,  not just sitting there blindly running other people’s computer codes.  (Although,  I did use computer codes,  and even wrote some myself.)  I have informally published several articles on my blog site that describe how some of this ramjet work was done.

Ramjet & Closely-Related Articles (there are others,  but these are the best):

9-1-2025:            On Pressure Vessels

6-1-2024:            Ramjet Ablative Liners

4-23-2024:          Presenter at Workshop (NC State U meeting on high temperature materials)

2-13-2024           GW's Ramjet Book Is Now Available 

10-1-2023            Basic Thermal Results for High Speeds

9-1-2023              Purported SR-72 Propulsion

12-2-2022            The Unchoked Gas Generator As A Throttle For Gas Generator-Fed Ramjets

12-1-2022            How Ramjets Work

10-30-22              Plasma Sheath Effects in High Hypersonic Flight

6-1-22                  About Hypersonic Vehicles

11-2-21                The “Warm Brick” Ramjet Device (nonpropulsive application to an infrared decoy)                                 [also the 11-2-21 update to this catalogue list]

10-1-21                Use of the Choked Pintle Valve for a Solid Propellant Gas Generator Throttle

8-2-21                  The Ramjet I Worked On the Most

7-1-21                  Another Ramjet I Worked On

11-9-20                Fundamentals of Inlets

3-3-20                  Ramjet Flameholding

2-16-20                Solid Rocket Analysis (applies to ramjet for boosters)

2-4-20                  One of Several Ramjets That I Worked On

1-2-20                  On High-Speed Aerodynamics and Heat Transfer

11-12-18              How Propulsion Nozzles Work

7-4-17                  Heat Protection Is the Key to Hypersonic Flight

6-12-17                Shock Impingement Heating Is Very Dangerous

12-10-16              Primer on Ramjets

12-21-12              Ramjet Cycle Analyses

These are located on http://exrocketman.blogspot.com,  along with many others on a wide variety of subjects. 

There is a navigation tool on the left of that page.  For the article you want,  you only need its publication date and its title.  Use the navigation tool:  click on the year,  then the month.  Then click on the title if you need to.  The data you need are in these lists.

If you click on one of the figures,  you can see all of them enlarged.  You see nothing but the figures,  though.  There is an “X-out” from this view,  upper right of screen.

At the end of any given article,  there is also a list of search keywords assigned to it.  If you click on “ramjet”,  you will only see the articles bearing that keyword.  The same is true of the other keywords.

Here follows a photo of one of the ramjets I worked on:  ASALM-PTV.  It is hanging under the wing of an A-7 Corsair-II,  an aircraft my father designed.  I always considered this photo a sort of “family portrait”. 

 

ASALM-PTV Ramjet Vehicle Underwing of A-7 Corsair-II

Some of those ramjet articles overlap with the next list.  That next list is of aerothermodynamics and heat transfer-related articles.  Some of these relate to high-speed atmospheric flight,  and others to atmospheric entry from space.  Those two scenarios are quite different,  in that atmospheric flight is a steady-state equilibrium problem,  while atmospheric entry is mostly a transient heat-sinking problem.  The search keyword for these is “aerothermo”.  Clearly,  I was adept at multiple specialties.

Aerothermodynamics & Heat Transfer Articles:

8-2-2026            What Nozzle Designs to Use Where, &Why

7-1-2026            Quick First Cut at Orion Entries (lunar)

6-1-2026            Entry Study (probes+Apollo, Earth & Mars)

5-1-2026            Entry By-Hand (how-to article)

4-28-2026          Preliminary Evaluation of Artemis-2 Heat Shield

3-01-2026          Ramjet Data Re: Heat Shields  

2-1-2026               Rocket Nozzles

11-2-2025             Get Acquainted Info: High Speed Vehicles

4-12-2025             Ballistic Coefficient Study for Earth Entry

7-2-2024               Recent Heat Protection Items, 3 of 3

6-1-2024               Ramjet Ablative Liners

5-23-2024:            Entry Concept Screening

4-23-2024:            Presenter at Workshop (NC State U meeting on high temperature materials)

1-2-2024              Airplanes on Mars?

12-9-2023            Overall Study Results:  Propellant From Moon

11-22-2023          How the Suborbital "Hopper" Calculations Were Made and With What

11-21-2023          Upgraded Rocket Hopper As Orbit Taxi

11-4-2023            Surface Freight Transport On Mars (not actually rocket,  but related)

11-1-2023            Rocket Hopper For Mars Planetary Transportation

10-1-2023            Basic Thermal Results for High Speeds

9-1-2023              Purported SR-72 Propulsion

5-1-23                  Heat Shields

2-4-23                  Rocket Nozzle Types (bells and aerospikes)

9-18-22                Plasma Sheath Effects in Hypersonic Flight

7-3-22                  Early High-Speed Experimental Planes

6-1-22                  About Hypersonic Vehicles

4-1-20                  Entry Heating Estimates

1-2-20                  On High-Speed Aerodynamics and Heat Transfer

1-9-19                  Subsonic Inlet Duct Investigation

1-6-19                  A Look At Nosetips (Or Leading Edges)

1-2-19                  Thermal Protection Trends For High-Speed Atmospheric Flight

11-12-18              How Propulsion Nozzles Work

7-4-17                  Heat Protection Is the Key to Hypersonic Flight

6-12-17                Shock Impingement Heating Is Very Dangerous

11-17-15              Why Air Is Hot When You Fly Fast

8-4-13                  Entry Issues

3-18-13                Low-Density Non-Ablative Ceramic Heat Shields

1-21-13                BOE Entry Analysis of Apollo Returning From the Moon

1-21-13                BOE Entry Model User’s Guide

8-19-12                Ballute Drag Data

8-19-12                Blunt Capsule Drag Data

7-14-12                “Back Of the Envelope” Entry Model

I was also a rocket propulsion engineer,  mostly in solid composite propellants.  However,  from the chamber outlet through the nozzle,  the ballistics of all rockets are the same,  including liquid propellant rockets.  If you can allow for any gas bled off and dumped overboard for turbopump operation,  then the very same ballistics apply,  right down to the chamber pressure vs flow rate calculation. 

Further,  the estimation of vehicle performance from the simple rocket equation can be made quite accurate,  if you know how to apply “jigger factors” in the appropriate places for gravity and drag losses,  and if you know what values of these “jigger factors” to apply.  I have been very successful at doing this kind of work. The following list shows that,  and mostly shares the “launch” and “space program” keywords.  While still a graduate student,  I spent a summer doing advanced configuration and mission work at what was then LTV Aerospace,  working on its "Scout" 4-stage solid satellite launcher. 

Rocket Ballistics and Rocket Vehicle Performance articles:

8-2-2026          What Nozzle Designs to Use Where, &Why

7-26-2026        Kudos to SpaceX for Flight 13

7-1-2026           Quick First Cut at Orion Entries (lunar)

6-1-2026           Entry Study (probes+Apollo, Earth & Mars)

5-27-2026         Kudos to SpaceX for Flight 12 

5-19-2026         Launch to Low Orbit Study (SSTO, TSTO)

5-18-2026         Launch Vehicle Rough-Out (SSTO, TSTO)

4-28-2026         Preliminary Evaluation of Artemis-2 Heat Shield

4-14-2026         Elliptic Departure and Arrival

2-21-2026         Space-Based AI?  Not Easy!

2-1-2026              Rocket Nozzles

1-1-2026              Landing Pads for Rocket Vehicles

12-1-2025            Criteria for Rough-Field Landings

11-11-2025          Where Should the New Space Stations Be Located?

10-16-2025          Going Back to the Moon

9-1-2025              On Pressure Vessels

8-1-2025               Air Launch to Low Earth Orbit

7-26-2025             Tank Design for Easy Cryogenic Transfers in Weightlessness

6-23-2025:            Starship Explosion (forensics)

6-1-2025               SpaceX “Starship” Flight Test 9 

5-1-2025              Vehicle Assembly and Refueling Facility in LEO

4-1-2025              About Nuclear Pulse Propulsion

3-13-2025            Rough/Soft Field Space Landings

3-7-2025              Upper-Stage Starship Failure,  Test 8

3-2-2025              Spin Gravity

2-21-2025            Asteroid 2024YR4 Threat

2-9-2025              There Is Nothing As Expensive As a Dead Crew

2-1-2025              Exploring Mars Is Not Settling Mars

1-25-2025            Initial Study for Tug Missions LEO to LLO

1-2-2025              SpaceX's Starship As a Space Tug (update looks at Centaur)

12-1-2024            Tug-Assisted Arrivals and Departures

11-1-2024            Getting to Low Earth Orbit and Back

10-13-2024          Starship/Superheavy Flt. Test 5,  13 Oct '24

10-1-2024            Elliptic Capture

9-13-2024            What Went Wrong? (problems with Starliner and at Boeing in general )

9-1-2024              Rocket Equation-Based Launch Vehicle Analyses

7-2-2024              Recent Heat Protection Items, 3 of 3

5-3-2024              Entry Concept Screening

4-23-2024            Presenter at Workshop (NC State U meeting on high temperature materials)

4-4-2024              Ascent Compromise Design Trade Study

4-3-2024              Bounding Analyses for TSTO

4-2-2024              Bounding Calculations for SSTO Concepts 

2-25-2024            Tricky Landing

3-3-2024              Launch to Low Earth Orbit:  1 or 2 Stages?

3-4-2024              Launch to Low Earth Orbit:  Fixed Geometry Options

9-1-2023              Purported SR-72 Propulsion

6-20-23                TSTO Launch Fundamentals

6-6-23                  Frontal Thrust Density In Rockets

2-4-23                  Rocket Nozzle Types (bells and aerospikes)

10-27-22              Getting to Low Earth Orbit  (vertical ballistic launch versus lifting ascent)

10-1-22                Rocket Engine Calculations (how to rough-out or reverse-engineer, ex: Raptor-2)

9-7-22                  Two-Stage Reusable Spaceplane Rough-Size (VTO HL both stages)

8-4-22                  Engineering Lander/Rover for Mars

5-1-22                  Investigation:  "Big Ship" Propellant From the Moon vs From Earth (added to list as part of Update 5-1-22)

4-2-22                  Earth-Mars Orbit-to-Orbit Transport Propulsion Studies (added to list as part of Update 5-1-22) 

2-1-22                  A Concept for an On-Orbit Propellant Depot

8-18-21                Propellant Ullage Problem and Solutions

3-15-21                Reverse Engineering Estimates: Starship Lunar Landings

3-9-21                  Reverse-Engineering Starship/Superheavy 2021

3-5-21                  Fundamentals of Elliptic Orbits (delta-vee requirements)

2-9-21                  Rocket Vehicle Performance Spreadsheet (rocket vehicle performance)

7-13-20                Non-Direct to the Moon with 2020 Starship

7-5-20                  How the Spreadsheet Works (Starship to Mars)

7-5-20                  2020 Starship/Superheavy Estimates for the Moon

7-3-20                  Cis-Lunar Orbits and Requirements

6-21-20                2020 Starship/Superheavy Estimates for Mars

5-25-20                2020 Reverse Engineering Estimates for Starship/Superheavy

2-16-20                Solid Rocket Analysis (solid ballistics & more)

11-21-19              Interplanetary Trajectories and Requirements

10-22-19              Reverse-Engineering the 2019 Version of The Spacex “Starship” / “Super Heavy” Design

9-26-19                Reverse-Engineered “Raptor” Engine Performance (liquid ballistics)

9-16-19                Spacex “Starship” as a Ferry for Colonization Ships

9-9-19                  Colonization Ship Study

11-12-18              How Propulsion Nozzles Work (rocket, ramjet, & turbine; plain & free-expansion)

9-11-18                Velocity Requirements for Mars

8-23-18                Back-of-the-Envelope Rocket Propulsion Analysis (rocket vehicle performance)

4-17-18                Reverse Engineering the 2017 Version of the Spacex BFR

10-23-17              Reverse-Engineering the ITS/Second Stage Of the Spacex BFR/ITS System

3-18-17                Bounding Analysis for Lunar Lander Designs (rocket vehicle performance)

3-6-17                  Reverse-Engineered “Dragon” Data (rocket vehicle performance)

8-31-13                Reusable Chemical Mars Landing Boats Are Feasible (rocket vehicle performance)

In 2009,  I attended an asteroid defense conference in Granada,  Spain,  as a poster paper presenter.  I have since written some articles about asteroid defense.  Unfortunately,  the asteroid defense capability picture hasn’t changed much since my 2009 attendance at that conference.  Again,  the latest are the best and most up-to-date.   Be aware that “NEO” (Near Earth Object) includes comets as well as asteroids as threats.  Comets may be the more difficult to defend against,  because of the surprise nature of the detection and orbits.  These articles all share the “asteroid defense” keyword.

Asteroid Defense Articles:

5-8-2025               Re-Entering Space Junk Threats

2-21-2025            Asteroid 2024YR4 Threat

8-30-20                Asteroid Threats  (current status assessment:  not good)

6-3-20                  On the Manned Spacex Launch

7-14-19                Just Mooning Around (asteroids plus Mars)

12-13-13              Mars Mission Study 2013 (what takes you to Mars takes you to asteroids)

4-21-09                On Asteroid Defense and a Good Reason for Having National Space Programs

I have also applied my wide-ranging knowledge to the problems of atmospheres to breathe while in space,  and the kinds of spacesuits that might best serve our needs.  Again,  the latest is the best and most up-to-date.  But I have been looking into these issues for some time,  as indicated by the dates on these articles.  These all share the “spacesuit” keyword.

Space Suits and Atmospheres Articles:

7-8-2025              Oxygenation Issues for Habitats and Space Suits

1-2-22                  Refining Proposed Suit and Habitat Atmospheres (update 1-2-22) best case and easiest-to-remember cases,  plus an independent estimate of the utter min suit pressures feasible

1-1-22                  Habitat Atmospheres and Long-Term Health (update 1-1-22)  adds a long term hypoxia criterion for the habitat in addition to short term criteria for the min-P suit

3-16-18                Suit and Habitat Atmospheres 2018

11-23-17              A Better Version of the MCP Spacesuit?

2-15-16                Suits and Atmospheres for Space

1-15-16                Astronaut Facing Drowning Points Out Need for Better Space Suit

11-17-14              Space Suit and Habitat Atmospheres

2-11-14                On-Orbit Repair and Assembly Facility

12-13-13              Mars Mission Study 2013

1-21-11                Fundamental Design Criteria for Alternative Space Suit Approaches

One of my favorites is the MCP (mechanical counter pressure) version of the spacesuit.  This was pioneered by Dr. Webb in the 1960’s as a possible suit for the Apollo missions to the moon.  It is not a full pressure suit at all,  but essentially a tight garment that simply squeezes the body.  It is porous,  so that you sweat right through it to cool,  just like ordinary street clothing.  But this design was tested quite successfully in 1968 for 30 minutes in a vacuum chamber,  at way above the equivalent “vacuum deathpoint” altitude.  Photo follows:

Webb’s MCP Space Suit:  Helmet,  Backpack,  and Supple Garment Total 85 Lbs

The reason why I like this approach over Dava Newman's designs is that Webb's designs are essentially vacuum-protective underwear that can be easily laundered.  Over them you wear whatever unpressurized clothing you need for protection from from heat,  cold,  and mechanical hazards.  All of these are separate,  easily laundered items.  I think the "one garment that does everything" approach,  that we have been using since about 1960,  is wrong.  "Mix and match" is way more flexible.

Besides vacuum death and microgravity disease,  there is also a radiation hazard to worry about in space.  But,  it is not quite what you think:  there are two completely different hazards to worry about.  On Earth,  we have two kinds of protection:  the atmosphere,  and the magnetic field.  In low Earth orbit,  we have only the magnetic field.  Outside the magnetic field,  going to the moon or anywhere else,  there is no protection.  Yet these things can be quantified,  and some of it shielded fairly effectively.  What got me started on this topic were the dangers posed by the nuclear disaster in Fukushima,  Japan.  Keyword “radiation”.

NASA has since lowered its career exposure limits below the older values I had obtained from them.  That avoids the slight chance of cancer late in life due to galactic cosmic ray exposure over long times in space.  But,  it makes passive shielding design bulkier,  heavier,  and more difficult to design.  It's really a trade-off.  However,  NASA still has not faced up to the erratic but intense floods of radiation from solar eruptions.  They haven't yet killed a crew from this,  although they came close to that during Apollo.  But if they don't address this,  they will kill a crew,  once we move out beyond the Van Allen belts,  and try to stay there.  That includes the return to the moon.  

Radiation Hazard Articles:

10-5-18                Space Radiation Risks:  GCR vs SFE

4-11-15                Radiation Risks for Mars Trip

5-2-12                  Space Travel Radiation Risks

3-24-11                Radiation and Humans

3-17-11                Follow-Up On the Japan Nuclear Crisis

3-15-11                On the Nuclear Crisis In Japan

On a lighter note,  I have long been interested in pulsejet engines,  especially valveless pulsejets.  While teaching math at TSTC,  Waco,  I became involved with mentoring a student who was also interested in pulsejets.  I and a colleague assisted this student in making his own valveless pulsejet engines,  which attention and involvement also turned this student into an “A” student in math!  Keyword “pulsejet”.

That student built a small engine that eventually pushed an old golf cart around,  and then a much bigger engine which we together fired up out here on my farm homestead.  Photos of the two engines follow:

Smaller Student-Built Valveless Pulsejet Engine (Later Pushed a Golf Cart)

Larger Student-Built Valveless Pulsejet Engine

Pulsejet Articles:

5-20-12                Recommended Broad Design Guidelines For Valveless Pulsejet Combustors

4-30-12                Big Student Pulsejet an Even Larger Hit at TSTC

3-6-12                  Student Pulsejet a Hit at EAA Meeting

11-12-11              Student Pulsejet Project

I have been interested in ethanol fuels since my early days in college.  When I went to work for what is now Minnesota State University,  after my 20-year career in aerospace defense work ended,  I got more serious about it.  My next job was at Baylor University in Waco,  Texas,  and it dealt directly in alternative fuels for aircraft.  The scope of that included ethanol (and an ether) as piston-engine fuels,  and biodiesel-jet fuel blends as turbine fuels,  plus STC work with the FAA,  and also experimental engineering research work,  as well as classroom teaching. 

Not too long after leaving Baylor,  I began my own experimental engineering research at home,  using E-85 ethanol fuel,  and stiff ethanol blends,  in a variety of vehicles.  Those would include straight E-85 ethanol fuel in an old farm tractor and in an old-time air-cooled VW beetle,  plus stiff ethanol blends in a variety of completely-unmodified cars and 4-stroke lawn and garden equipment.  I basically recommend up to E-35 blend strength,  as a “drop-in” fuel,  for just about any 4-stroke piston engine. 

The keywords are “ethanol” and “old cars” for most of these articles.  Once again,  the latest is the best and most up-to-date.

Articles About Ethanol and Ethanol Blends in Vehicles:

9-1-21                  Making Stiff Blends At the Gas Pump

11-3-13                Aviation Alternative Fuel Compatibility Issues

11-2-13                An Update on Ethanol Fuel Use

8-9-12                  Biofuels in General and Ethanol in Particular

5-4-12                  Energy Storage: Batteries vs Unpressurized Liquid Fuels

6-12-11                Another Red-Letter Day

5-5-11                  Ethanol Does Not Hurt Engines

2-12-11                “How-To” For Ethanol and Blend Vehicles

11-17-10              Nissan Mileage Results on Blends

11-12-10              Stiff Blend Effects in Gasoline Cars

12-15-09              Red Letter Day:  Ethanol VW Experiment Complete

7-1-09                  Another Antique Comes Out of Storage

I have returned part-time out of retirement to help a friend with his auto repair business.  I was once ASE-certified as a condition of employment while teaching at Minnesota State in its Automotive and Manufacturing Engineering Technology department.  Before that,  I did most of my own automotive maintenance and repair work.  Accordingly,  I have posted some articles about basic car care,  plus one funny.  These all share the “old cars” and “fun stuff” keywords. 

I have since gone back into retirement.  My friend now has a real mechanic,  who knows more than I do,  and is much more experienced,  and faster. 

Automotive Care Articles:

8-22-22                Automotive Work (another "funny")

3-4-22                  Understanding Your Tires (added to this list as update 5-1-22)

12-3-20                Blinker Fluid (the “funny”,  and it is a sight gag)

8-20-20                Underhood Check

7-25-20                Taking Care of Car Batteries

When I returned to the rocket plant in McGregor for my second employment there,  the family and I acquired an old farm outside McGregor as our home.  We have been there ever since.  This place was largely covered in shin- to knee-high prickly pear cactus,  so thick there were few trails through it.  After grubbing it out of the house’s back yard with hand tools,  I decided there had to be a better way to do this cactus eradication. 

I tried a variety of mechanical drags behind my old farm tractor for some 15 years without success.  The results were always the same:  it looked better for a while,  but returned worse than ever before,  within months.  My neighbor was trying shredding at 1 inch off the ground.  Eventually that worked,  but required the neighbor to be out there shredding,  every single day,  the same ground over and over,  for 6 (or more) years.  The neighbor also tried spraying herbicides on one patch of ground,  which took 3 years to show results,  but then totally reinfested within another 2 years.

I then tried to build a “scooper-upper” out of scrap steel.  The idea was to bust the aboveground cactus loose from its roots,  and catch it on a tarp towed behind the “scoop-upper”,  for disposal in a burn pit.  It completely failed to work,  because when the tool hit the cactus and busted it loose from its roots,  it fell forward in front of the tool,  instead of backward onto the deck.  The tool then just ran over the top of the cactus debris.  I gave up in disgust when this failure-to-scoop happened.

I went back up a few months later to salvage the steel,  and saw something totally unexpected:  the cactus was dead and gone wherever the tool had been towed!  Grass was growing in the cow pasture where the cactus had been.  It did not take very long to understand that the aboveground cactus foliage had been crushed and damaged passing underneath the heavy tool,  such that the pads dried out and died,  before they could put down new roots from the thorn sites in contact with soil.  They had completely composted away over those months.

I “played” with this tool to get it just “right”,  and started killing acres of prickly pear quite effectively,  and with very little time and effort involved.  In fact,  I still have this very same experimental prototype,  and it still works today.  This prototype led to me filing a patent on the cactus tool in 2002. 

I revised the design to something more producible from real steel stocks,  and built two production prototypes that worked just as well as the original experimental prototype,  but were easier to build.  Then,  with the patent in hand as of 2004,  I began building and selling these tools to the public.  My first customer wouldn’t wait for a real production tool,  and insisted on buying one of the two production prototypes.  I still have the other one.  I still use it,  and it now serves as an experimental test bed for new features,  too.

As time went by,  it quickly became apparent that other folks had rockier land,  or land with tree stumps.  I changed the design twice,  to add a heavier stabilizing snout,  plus a “barge front” wedging surface to get over small rock outcrops.  This was quite successful,  and is embodied in the tools still built and sold today.

A close friend wanted to do cactus-killing for hire,  and bought a “one-off” design from me.  I also helped him build and modify a few more tools,  until the “commercial version” was defined:  a really tough snout,  a big “barge front”,  and retractable wheels to facilitate stepping over obstacles,  plus easier loading up ramps onto trailers. 

When that friend retired,  I revised his “commercial” design into something that used a common core tool chassis with my “homeowner grade” plain tool.  This common core chassis had the big barge front,  and used either a tough snout for the “plain tool”,  or a longer tough snout for the “hydraulic tool”,  that was also fitted with retractable wheels operated hydraulically.  I sell both versions to this very day.  Both are towed on a chain bridle behind a farm tractor’s drawbar.

I am working on a third version that could be an alternative implement affixed to the hydraulic boom of a skid-steer loader.  It uses an already-available “universal” adapter plate to accomplish this,  as a quick-change item.  There is nothing to report here yet about that project,  but the “plain” and “hydraulic” tools are well-described in a series of articles on “exrocketman” under the keyword “cactus-killing”. 

These two versions are shown in the photo,  with the plain tool in the foreground,  and the hydraulic tool in the background.

Foreground:  Plain Tool;  Background:  Hydraulic (Wheeled) Tool

The new skid-steer version has been tested and revised to a form that not only works,  but is more easily manufacturable.  It is now patent pending. 

Articles Related to Cactus Eradication:

2-9-17                  Time Lapse Proof It Works

7-30-15                New Cactus Tool Website

1-8-15                  Kactus Kicker Development

1-8-14                  Kactus Kicker:  Recent Progress

10-12-13              Construction of the Plain Cactus Tool

5-19-13                Loading Steel Safely (Cactus Tool)

12-19-12              Using the Cactus Tool or Tools

11-1-12                About the Kactus Kicker

12-28-11              Latest Production Version of the Kactus Kicker

 Update 12-1-2021:  these articles are more-or-less forensic analyses of various events:

7-26-2026          Kudos to SpaceX for Flight 13

6-9-2026            Close Call at Newark

5-27-2026          Kudos to SpaceX for Flight 12

6-23-2025            Starship Explosion (forensics)

6-1-2025               SpaceX “Starship” Flight Test 9

3-13-2025            Rough/Soft-Field Space Landings

3-7-2025              Upper-Stage Starship Failure,  Test 8

2-9-2025              There Is Nothing As Expensive As a Dead Crew

10-13-2024          Starship/Superheavy Flight Test 5,  13 Oct 2024

9-13-2024            What Went Wrong?  (problems with Starliner and at Boeing)

7-7-23                  On the loss of the "Titan" Submersible  (added 7-18-23)

4-25-23                Starship/Superheavy Flight Test

12-1-21                The Seal Failure in the SRB That Doomed Challenger

12-10-20              Spacex Test Flight Results in Explosion

9-1-20                  On the Beirut Explosion

5-4-18                  Some Thoughts on the Anniversary of the West Explosion

11-1-14                Two Commercial Spaceflight Disasters in One Week

7-9-13                  On the Asiana 214 Crash

7-9-13                  On the Train Wreck in Quebec

4-18-13                Fertilizer Explosion in West,  Texas

9-23-11                Air Races,  Air Shows,  and Risks

6-3-10                  Plenty of Blame to Go Around for the Disaster in the Gulf

5-20-10                It really was the North Koreans who sank the South Korean ship

Update 1-1-23:  these are the articles related to towed decoys:

Between my tenures at the McGregor rocket shop,  I worked at what was then Tracor Aerospace in Austin,  Texas,  doing aircraft and ICBM countermeasures work.  The bulk of this related to towed aircraft decoys,  which are more advanced aircraft countermeasures against missiles than the traditional chaff and flares.  I did all sorts of lab,  wind tunnel,  and flight tests with these things.  To a great extent,  I had to design my own tests,  test hardware,  and equipment,  too. 

Tracor Austin became part of British Aerospace after I left to go back to the rocket shop in McGregor,  and it closed entirely,  only somewhat later.  When you combine the typical corporate management misbehavior with the massive defense industry contraction that happened after the fall of the Soviet Union,  this plant closure outcome is entirely unsurprising.  That was as true for the rocket shop as well as for Tracor.  And it is why I had to leave the aerospace defense industry entirely,  after being laid off in late 1994 due to the rocket plant closure in McGregor.

My work at Tracor in towed aircraft decoys related to two distinct types of decoys:  towed hard body decoys,  and towed ribbons.  The hard bodies are exactly that:  some sort of small airframe towed behind the aircraft that it is intended to protect,  on some sort of towline.  These could be radar (RF) decoys to replace chaff,  or they could be infrared (IR) decoys to replace flares and jammers.  I worked on both of these towed decoy types (RF and IR).  Towed RF decoys are now operational with the air forces of multiple nations,  because they really work.

The towed ribbon decoys are quite different,  being rather similar to windsocks and soft towed gunnery targets.  The technologies supporting this concept apply only to RF,  and are restricted to only extreme-low observables aircraft.  I also worked on these.  One huge issue is stable tow for extended periods of time,  when the “flapping-flag” effect wants to destroy them in mere seconds at jet aircraft speeds. 

Obviously,  deployment,  especially very rapid deployment,  is another huge issue with these ribbon decoys,  as well as with the hard body decoys. Solving it requires expertise in dynamics as well as aerodynamics,  plus knowledge of all sorts of mechanisms. 

Here is the list of my towed decoy articles available as of this update.  Future updates may add more. 

1-1-23                  Towed Hardbody Decoys  (could IR or RF)

11-2-21                The “Warm Brick” Ramjet Device (nonpropulsive application to an infrared decoy)   

Later                     possible articles on deployment and on towed ribbons