This information comes from the Bridgestone Commercial Tire site:

Dear Tire Doctor,

{With air pressure and tire temp sensors installed in aluminum wheels, what kind of temperatures should be observed while driving in 90- to 100-degree temperatures?

What air temperature reading would be too high? I am using the Smart Tire system.


Dear Tom,

Thank you for the opportunity to be of assistance.

The answer to your question depends on a number of factors, and quite frankly, there is no hard and fast rule.

There are basically three types of tire temperature measurements:

1. Probes inserted into the tire
2. Contained air temperature (which your system uses)
3. Tread (surface) temperature

A probe inserted into the tire - into either the belt edge or the bead area - the hottest points of the tire - is the most accurate method; however, it can only be performed under controlled conditions.

The contained air temperature method is the next most accurate, however, it is affected by the mounting system of the sensor - if the sensor is attached to the wheel, it will pick up heat from the wheel (which is picking up heat from the brake drum); and if it is attached to the tire interior, it will pick up heat from the casing.

Tread (surface) temperature is the least accurate; since measurement is normally performed by a hand-held unit, thus hampering repeatability, plus the question of where do you measure? The ribs will be cooler than the grooves, and the center will be cooler than the shoulders, etc. So, while all this has so far done little to answer your question, we hope it has shed some light as to why we are being a bit reserved in our answer.

Now, what can I say to try to address your question?

While this is not set in stone: A very general rule of thumb is that a properly inflated/loaded tire, when up to operating temperature - one hour or more of operation - will typically run about 60 degrees F hotter than the ambient temperature. Anything above 200 degrees F could lead to tire degradation and you need to investigate for a problem.

Best regards, Tire Doctor}

Since I have installed Tire Safe Guard on my tires I am now much more aware of tire temps. I was surprised to find that operating temps from 176 to 230 degrees is acceptable, depending on the tire.

In researching more about temps and pressure I found some interesting sites, one of them devoted to retreads and loaded with lots of information. There is also several movies on the Michelin site which Gary De pointed out in an earlier post. This other Michelin location give even more reference material about RV tires. With much of this tread about alternatives to expensive Michelin tires retreading poses some interesting possibilities. According to the Retread.Org our tires should be functional and safe for 100s of thousands of miles, depending on the condition of the casing. The big negative here is that most of our casings would be old by the time they were ready to have a retread applied. I am sure Joe C. and "Truk" will have some input on the quality of todays retreads such as Bandag. (Now owned by Bridgestone)

Personally I would prefer new Michelin rubber but with tires approaching a grand apiece it might be time to look for some alternatives. In the meantime good maintenance and proper pressure will insure that I get a long life out of my existing tires.