What is the "cold" temperature for tire inflation?

[wsc7050]

Hello quick question. My trailer tires instruct me to use 65 psi when cold. Well some days I start in the 30's and some days in the 70's. And for argument sake, let's say both of those days end in the 90's. I know from using my tire temp and pressure monitor that if I put 65 psi in at 30 degrees and ran it to 90 degrees it would be different than if I put it in at 70 degrees and then ran it to 90 degrees. So should I be aiming for 65 psi for the temp I would spend most of the day towing at, or?
Thanks in advance!

[2oldman]

This is why a TPMS is so convenient. You know exactly what pressure you're running right now.

[PDX_Zs]

You should also know your Hot PSI.

This allows you to check during a drive.

[wsc7050]

Thanks everyone!

[phillyg]

Cold means not driven on. Ambient temps should not be considered. I know it's counter-intuitive, but that's from tire mfgrs. info.

[CaLBaR]

Second Chance wrote:
One caveat... if the sun is shining on the tires on one side of the vehicle for a while before you, er..., make it outside, you may find up to a 10 PSI difference between the pressures on the sunny and shady sides (with a 20-30 degree difference in temperature). Often times I end up having to check tires on travel days when I'm up and about earlier - especially on the truck where the tires aren't shaded by the slides. The differential may not be as great on a passenger car tire inflated to 32 PSI as it is on E-rated truck tires at 65 - 80 PSI or G-rated trailer tires at 110 PSI. Bottom line, though, I always make sure it's a cold tire before I change the pressure one way or the other.

Rob

Agreed. Guess I am up usually before the sun hits the tires when we travel.

[jerseyjim]

Another "caveat"...if mine is in storage over the winter...my tires seem to lose 7-10 psi.

Love that word.......

[Second_Chance]

One caveat... if the sun is shining on the tires on one side of the vehicle for a while before you, er..., make it outside, you may find up to a 10 PSI difference between the pressures on the sunny and shady sides (with a 20-30 degree difference in temperature). Often times I end up having to check tires on travel days when I'm up and about earlier - especially on the truck where the tires aren't shaded by the slides. The differential may not be as great on a passenger car tire inflated to 32 PSI as it is on E-rated truck tires at 65 - 80 PSI or G-rated trailer tires at 110 PSI. Bottom line, though, I always make sure it's a cold tire before I change the pressure one way or the other.

Rob

[CaLBaR]

To answer the Ops question, cold tire pressure is first thing in the morning before driving or after the tire has sit for several hours. If it is 30 out then check at 30 and if it is 70 out check at 70 even if both days end at 90. It is a reference check. The manufacturers take into account that during the day and during the drive the tires will heat up.

[Tvov]

old guy wrote:
a cold tire is one that has been sitting, say over night or several hours with out movement

This is what I figure. I check tire pressure in the morning.

[bobndot]

Similar to how deer know to cross the road at a 'deer crossing' .

[old_guy]

a cold tire is one that has been sitting, say over night or several hours with out movement

[ChuckV1]

Always, always, always use cold temperature stated on the side of your tire, Check an inflate the tires when they are cold, never, never deflate a hot tire to a cold temperature.

If you think a tire is going flat and you check it an it reads low, then inflate the tire to match the already warm/hot other tires, then check that tire again the next time you stop again, if it's low again then seek out a tire shop to get tire repaired or change to your spare if you have one ...

Only add air if the tire is going flat, temps will very on different road surfaces, cement, asphalt, hot and cold ambient temperatures. They will always gain air when hot and loose when cold unless they a filled with nitrogen an then they will still gain some or loose some but the temperature of the tire will however run cooler overall ...

I always check my tire pressure 1st thing in the morning before starting out, i check the temperatures of the tires and axle hubs during the day when I stop to make sure they are not overly hot to the touch, some people use lazier gauges to do this same thing.

Safe travels