Does any tire company have some "Magic Rubber:?

 In Sept 2024 I wrote on the Operational limits on ST type tires. I suggested that the published 65 MPH was a realistic compromise but apparently many people think they can get tires with some "Magic Rubber" in them so I am again writing about the "Speed Rating" of ST type tires.

 In the US "Speed Rating" is really a measure of tolerance for high heat and is based on a 10-minute long test with speed increasing every 10 minutes till the tire fails. In Europe, Asia and the rest of the world, they do not offer an ST type tire because their speed tests are more realistic and stringent.

When ST type tires were introduced to the US market some 45 years ago, they were given a higher load capacity rating than a same-size LT tire BUT the trade-off was STATED in the industry standards books as having a max operating speed of 65 mph. With 50 years of Tire design and testing under my belt, I know of no "Magic" rubber that will deliver greater load capacity for a given size and inflation without some trade-off.

There are only 5 variables that control operation speed. Size, Load, Inflation, speed and the ability to be rated for operation with passengers in the vehicle, so unless you invent some "magic rubber" you are limited by physics. Yes, materials have improved over the last 40 years after the switch to Radial construction and we have seen improvements in tire performance, but have you ever asked why a company can make a tire of the same physical size and same load capacity at a given inflation and somehow make one tire carry significantly more load than the other without some trade-off in operation speed?

If I had invented some "Super Magic Rubber" for ST type tires that gave them "Super Strength" why wouldn't I put the Super Rubber in the other tires I make and sell and take over the worldwide tire market? Any company can ignore reality and make a marketing decision and claim a "Speed Rating".

 

At what temperature reading of TPMS should I worry?

 Read a forum post with a question

 Hi all, very newbie here.

I have a 1/2 ton double axel travel trailer with ST225/75 R15E Goodyear Endurance Tires on it. I was  towing it today and my TPMS monitor alarmed because of tire temperature.

Now nothing extravagant, tires were between 75 and 82 PSI, running temps for all were not above 85 degrees.

The TPMS was at factory settings. I found this on the internet, this guy says 158 degrees is a standard alarm trigger for TPMS. Is there a critical do-not-exceed tire temperature?  What should I set the temperature tolerances at in the TPMS so it is not alarming with basic driving?

 

 Here is my response

 As an actual tire design engineer  who has been working with TPMS since 2002 I can suggest that you not worry about the "High Temp" warning as it is normally set to 158F. You need to pay attention to the PSI. I suggest the low pressure warning be set to the minimum psi required to support your MEASURED inflation level. I suggest that you never operate the tire in overload. TPMS Temperature is not reporting the hot spot of the tire as that point is located about 1/4" to 3/8" inside the shoulder of the tire. Rubber is an insulator so it does not transmit the heat energy to the tire inside air, TPMS temperature readings are closer to the temperature of the metal wheel, hub and wheel bearings as the metal does transmit the heat of these metal parts quickly. A high Temp reading from the TPMS without a significant increase in PSI is probably warning of a wheel bearing problem.