Tire temperature

[beemerphile]

just to be anal about the pressure rise, absolute should be used instead of gauge pressure to compute the percentage rise, so instead of 21% (9/42) its about 16% rise (9/57).

Agreed. It would be absolute for the gas equation, but I was just using the ratio of 1 psi for 10F rise to calculate it. When most rules of thumb for tire pressure rise say 5% pressure rise for best tire life and 10% pressure rise for best performance, they are using gauge pressure. 10% would be 40 to 44 psi and 5% would be 40 to 42 psi. That was the comparison I was making with the 20% number - twice the normal rise that most people would look for when trying to set cold pressure to a level that gets the tires to best operating temperature. I've never had one go up 9 psi after being run. And if I had gotten a 9 psi rise, I'd think my starting pressure was too low. But at 42 psi, that is not low. I'm still puzzled by the numbers.

 

[jspringator]

When I programmed the TPMS for my motorhome they advised to use the default settings for temperature.

I had a sticking caliper while on the BRP and the high temperature alarm went off. Never take a motorhome on the BRP.

 

[CYYJ]

...agreed that the theoretical rise is around 2.3-ish based on the math for that temp rise, but it seems like most TPMS users report much more than that, not sure what explains it.

I usually see a pressure rise (reported on the TPMS) of about 4 PSI after riding steadily for an hour or so, once everything has warmed up and stabilized. This doesn't concern me, because it is very similar to the pressure rise I see in automobile tires under the same conditions.

I have not noticed a significant difference in pressure rise between the front and back wheels, although the rear wheel is always significantly warmer than the front wheel after riding for an hour or so. I think the warmer rear wheel is perfectly normal - it's not exposed to as much airflow as the front wheel, it carries more weight, and it is exposed to warm air coming off the engine and the exhaust pipes.

Michael