An RVtravel.com reader recently asked about the wide temperature swings in Texas and its effect on tire inflation.
He said, “I check tire pressures regularly and monitor my tires with a TPMS. Most of the year it is not much of a problem, but here in TX, some days are going to be hot, really hot or extra hot, without much relief overnight. The problem comes during the variable short Texas winter season. Days can fluctuate from cold temperatures overnight, 30s-40s, and rise into the hot ranges in the day.
“My question is… On travel days, what condition should the tires be set for? Multiple changes each day are not practical and sometimes not possible when the tires are hot from use.”
My reply
As the “tire guy” for RVtravel.com, I can offer some information that I hope will help you out.
1. You do not need to be chasing tire pressure during the day if the pressure is correct in the morning before the tires warm up, or even if they somehow show much cooler in late afternoon. However, that is not very likely, even if you travel to a much cooler location.
2. Basically, what we are trying to do is to protect against running tires at psi lower than found in the tables based on the measured load of your RV. Having a psi higher than normal, because of changes in the ambient temperature, is almost never a problem.
3. Tires are very tolerant of temperature and pressure changes seen during a travel day. We Tire Design Engineers test tires and rubber compounds from well below freezing to way above 100° F.
What I do
In my Class C, I tend to run +10 psi over the minimum inflation found in the tables based on my truck scale weight readings. This margin protects against running underinflated. Tire psi only changes by about 2% with a change in temperature of 10° F. Therefore, even if the temperature goes up 50° F, I would only expect to see an increase of 10% in tire psi, which is no problem for undamaged modern tires.
With the introduction of TPMS, people are now confronted with information on tire temperature and pressure variation that they have never seen over the last 30 to 50 years of driving, so I can understand your concern.
I have done a couple of cross-country drives with the air temperature changing by well over 50°F to 70°F, but I never saw a tire pressure increase to a “dangerous” level.
Running tires 10% low is not good for the long-term life of tires. Running a tire 20% low is considered to be “running flat” for many applications and potentially could result in a tire failure.
Conversely, running 10% more psi than what is found in the “Load & Inflation” tables is no problem. Even running +20% psi is probably only going to result in tire tread wear a little bit.
I hope this helps. You can contact me directly if you still have questions.
Roger
Reply from the RV owner:
“This is great information; it clarified the issue for me and changed some misunderstandings I had. Your recommendations will simplify things for me.”
*****
Roger Marble
MORE FROM ROGER ON TIRE PRESSURE
- Learn the basics of setting tire pressure and testing TPMS
- My RV tire pressure is showing a significant increase. Is this OK?
- Is the tire pressure too high?
- Should you adjust tire pressure when temps get colder?
- Do not adjust your tire pressure for ambient temperature
*****
If you have tire questions, check out Roger’s posts on RVtravel.com. There are hundreds of posts covering everything to do with tires.
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The downside to higher pressure is deteriorating ride quality. But don’t ever be low on pressure.