PSI Levels

[captbanjo]

So, now that my Tire Minder is up and running I have noticed something; in the morning, I set my G series Goodyear tires to 103 pounds thinking that they would rise up around the 110 maximum when I was on the road. Driving across Florida they went up to 116 PSI. I stopped at a rest stop and brought them all down to 110. I will see what they read in the morning. Meanwhile, I'm wondering if this is OK? Should tires that are rated to have a maximum PSI of 110 be OK up to almost 120 when they are running hot on the road?

[trustymopars]

Yes, the rating is cold psi, and the tires have reserve built into them to compensate for the psi raise due to heat. JT.

[DarMar]

We run ours at 100 psi cold and there is no need to worry if the psi increases by the amounts you indicate.

[Dam Worker]

I would tend to agree with Trustymopars as everything I have read and heard was always rated for cold PSI.

Tom Marty

[DQDick]

We run ours at 108-110psi and have seen them go as high as 126psi on the sunny side of the rig in 100 degrees plus. After 5 years and 45,000 miles they still look like new.

[1retired06]

Agree, cold PSI

[rames14]

As others have stated, cold PSI. As we add new devices, sometimes we have to think about what our devices are telling us. A number of factors affect tire pressure and temps as we ride down the road. And temp impacts pressure. Go to the load chart and set the pressure to the weight you are carrying (cold). You will notice heavily loaded areas of the trailer may increase more, crown on the road can increase friction and cause one side to increase more and as mentioned sun can also increase pressure. The best advice is get them aired to the proper pressure cold, set your alarms and react if it alarms or you see significant changes. For example, our first trip with tire monitoring, we had our under temp set to 70 and our over at 120. All of the tires were running toward the 120. Suddenly, one tire started to drop. I pulled over at the next pull off and had a slit in the sidewall. Safe travels.

[richfaa]

Set the PSI cold. We also noted on our TST system and also when we had the pressure pro system that there was a difference between the PSI setting at the monitor and the psi setting at the valve stem. The PSI setting at the TST monitor in the truck is 3PSI lower than the valve stem setting. We set the PSI at 110 at the valve stem. We also have 3 so called high quality Digital air gauges and none of then read exactly the same. The PSI readings that DQDICK post are not at all uncommon.

[CORattler]

Absolutely correct!

quote:Originally posted by trustymopars

Yes, the rating is cold psi, and the tires have reserve built into them to compensate for the psi raise due to heat. JT.

[TLightning]

Sometimes we tend to over think some of these issues. There is a tire guru on another forum, he says set the PSI in the AM before you start driving. Don't change it until the next morning, if necessary. Two things will affect the tire pressure (not including heating up when driving)...altitude change and/or outside air temperature.

[Mark N.]

Never let air out of a tire because the pressure is up after running it. Check and adjust pressures ONLY when tires are cold (By cold I mean having not been driven on.) Cold can be any ambient temperature at all. It doesn't matter if it's -18 degrees in Wyoming in Jan., or 118 in Phoenix in July, you check and adjust tires only after they have sat overnight.

[Buffalochip]

How does elevation affect pressure? I live at 5000 feet but my Montana is in Quartzsite Arizona at about 1000 feet or so but will be towing it from Quartzsite to home in a couple of weeks. Any thoughts?

[richfaa]

Never did any adjustment for altitude.

[mlh]

I've been keeping an eye on the pressure in my tires while my camper just sets. The sun can't get to the tires and yet the pressure will vary 4 pounds from a 40 degree morning to a 70 degree afternoon. My tires are set at about 80 pounds. With that much variation who is to say what they are set at.
Lynwood

[dieselguy]

"How does elevation affect pressure?" As altitude increases ... atmospheric pressure decreases. So a tire aired up to a given psi at say sea level will read a higher pressure at say 5000 ft. The same issue with air beds traveling in the mountains come to play here. For tires ... it is a minimal psi change with no cause for concern. On the same note it is generally accepted that for each 10 degree increase in temp, tire pressure increases about 1 psi

[Buffalochip]

Thanks diesel guy. I was just wondering. When you buy a bag of potato chips here, it looks like someone pumped air into the bag due to elevation #128513;

[rames14]

And at 7500 feet, ice cream pops the lid off.