Hot Tire Pressure

[dewilso]

If you are on the road and after while you need to adjust your air, but the air place is miles down the road, and the tires will be road heated, how can you determine a good pressure ? You leave Texas and it’s 100°, then, later, you are in Colorado, it’s 40°, your tire pressure monitor squeals every morning, it’s 50 miles to Discount Tire.......?

[Kirk W]

Many of us carry an air compressor. 

[dewilso]

Real helpful Kirk, thanks !

[Kirk W]

If you have a generator, get one that is powered by 120V as the better 12V ones will do it but take a very long time. 

[dartmouth01]

Like Kirk says, an air compressor and you can set your air pressures every morning if you like regardless where you are, and the temp.  As long as you set the high side of the range to a safe #, you shouldn't get over-limit readings if you go from a cool morning to a scorching hot afternoon (like the time I went from Lone Pine CA to Death Valley!).  I personally carry the Viair 88P, good enough for the 80psi rear tires on the truck.  If you have a MH with 100psi or such, the Viair 400RV will get you there!

[Optimistic Paranoid]

If you set your cold air pressure correctly in the morning, and stop and check it a couple of times a day to see what it is hot, you'll quickly get a feel for what a safe hot pressure is for your rig.

[Ranger Smith]

Just adjust the low pressure a little lower on your tpms.

[dewilso]

Thanks for all the helpful pointers for my present situation. They are all appropriate responses to the original question.

[oldjohnt]

Yeppers the tires say on the sidewall something like Max Load at 80 PSI Cold, so what's cold (you in the Arizona desert or Alaska) ????????? Late at night or early AM pressure is what I use regardless of where I'm at. One other safety check I've used is when I stop for gas shoot a temp gun on each tire to get a read on if any (perhaps under inflated and flexing and heating up) are way out of range. If so inspect and check immediately.

John T  NO tire expert by any means

[Optimistic Paranoid]

I'm not a tire expert either, but I can give you a link to somebody who is:

http://www.rvtiresafety.net/

Plus links to factory publications from Goodyear and Michelin:

https://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf

https://www.michelinrvtires.com/reference-materials/tire-guide-warranties-and-bulletins/

[JRP]

14 hours ago, dewilso said:

 If you are on the road and after while you need to adjust your air, but the air place is miles down the road, and the tires will be road heated, how can you determine a good pressure ? ......?

The pressure rises about 2% for every 10 degrees F. Get yourself one of the Digital IR (non-contact) Temp Sensors to read the tire surface temps (if your TPMS doesn't give temp readings). Like others, I also carry a portable compressor good up to 125 psi, since my MH tires need about 90 psi and many fuel station air outlets either don't have room for a 38 ft MH plus towed, or they don't work well at 100 psi. 

I made my fall transition from summer home to winter home this week. when I left the Colorado mountains early morning it was 24 F, and the normally 85-90 psi tires were reading 75 - 80. I did not add any air and 500 miles later in southern NM it was 80 F ambient and the tires were reading 105 psi.  As the experts advise its the cold temp pressure that matters, never let air out when the tires are hot. But when your "cold" varies from 24F to 80F you should adjust accordingly.  Most TPMS allow some flexibility in setting your base pressures and the range or % variation before setting off an alarm.