How hot is too hot? Tires

[Keith Moffett]

We have R12 Toyo tires all around.  The duals have a 'Cross Fire' air pressure control which shows yellow and has a line for 110 lbs pressure.  When they are over pressure the guage shows red.  They were fully red the other day even though we had driven only about an hour and in 70 deg. weather.  I did a pressure check and it read 120 lbs. (hot).  Max for the wheel is 120 lbs. (cold).  I cant help but think this would have been a problem had we been in 100 deg. weather.

Any opinions on this?

Keith

[Edward Buker]

Keith,

The tire companies always allow for heating in their load handling vs tire pressure tables as well as the max pressure limit. For the most part we ignore tire heating as an issue. I am sure that heavily loaded tractor trailers see even more tire heating then we do if that is any consolation. There is a case where your rims are rated with a max number and I am not sure how much that number is compensated but there must be a safety margin in all of this. If I was right at the max pressure tire limit of 120lbs cold and it was going to be 115 degrees out and I had a load margin to drop to 115lbs I might consider doing that but it is not a common practice by anyone I know. Running 110lbs cold vs a 120lb cold limit I would not worry about the tire heating issue.

Later Ed

[Keith Moffett]

That seems to make sense but there is a grey area there.  If we had been in hotter climate the high temp would be off the scale.  That leaves alot to chance on a 12 year old rim.  You are no doubt right Ed but it does make me wonder a bit!

Keith

[Gerald Farris]

Keith,
I run 120 PSI cold in my tires, the maximum cold inflation. I have commonly seen summer time hot tire pressures in excess of 140 PSI on my tire pressure monitoring system. This is a normal condition that you should not be concerned about. The tire pressure charts take the gain in tire pressure from road heat into consideration, and these factors are engineered into the tire construction.

The problem that you need to be concerned about is underinflation/overloading. Therefore, you should never deflate your tires to compensate for road heat, because this will lead to underinflation/overloading related tire failures.

Gerald