Tire Pressure Question

[Dthomas9572]

Hello,

After installing my new 315 tires on my 98 Featherlight, and after weighing I settled my tire pressure on 110 steers and 100 on drive and tags. I went on a trip from OKC to Minneapolis last week.

I am being extremely diligent about checking tires each time I leave on a trip and each morning during the trip

It was in the 70s (low) to 90's (high) in OKC. All pressure was perfect.

When I cked in Minneapolis (60's) low and 80's (high) I noticed the morning pressure had dropped 4 degrees equally on each tire. All tires were the same 4 degrees drop. I assume that this is natural due to different temps.

I decided to just keep the tires at that 4 degree drop knowing I was heading back to OKC where temps were higher again.

My question is is best to do this or should I air them up to my target temp in the future?

Thanks

[BadFitter]

According to: https://www.tirebuyer.com/education/tire-inflation-pressure-and-temperature#

"A good estimate is for every 10° fluctuation in air temperature, vehicle tire pressure will adjust by about 1 psi. So if outside air temperature decreases 30° from your last tire pressure adjustment, expect tire pressure to drop about 3 psi."

[Gil_J]

You're not going to hurt your tires if you properly inflate them in the colder climate and drive to slightly warmer climate.

Les, I've read the same in other places. What's strange is that's not consistent with what most TPMS systems reporr.

[Dthomas9572]

Now that I am back in OKC the tires are back to 110 on front and 100 on rears. This was only 10 degrees drop in temp and 4 degrees loss in tire pressure.

[Ck2hans]

I just got back from a trip where the sun was on the passengers side most of the day and the drivers side was shaded while driving. I noticed a 3-4 PSI increase in the sunny side. I assume it's the nature of the beast.

[Gil_J]

The tire pressure changes you both describe associated with outside temperature changes and the sunny side effect are what others experience, myself included.

[Dtjoint]

I learned something this week about tire pressure that I didn’t know. We are at a NW Bus Nuts rally at a new RV park that Guarantee RV built as part of their growing facilities in Junction City, OR. I decided to have the normal annual service done while we were here. They have a wheel lift system and I have never seen the underside of our bus so I paid them for their “full” service. When they were finished the report showed the drive and tag tires as over inflated.

I had set the tire pressure just before we left based on six wheel weighing of the coach a year ago so questioned how they could call them over inflated without having access to that report. They said they set the pressure to what was shown on the Country Coach placard in the bus. I had never even noticed such a placard so asked them to show it to me. Sure enough there is one on the wall beside the driver where the axle weight placard is located. It showed the same 110psi on the steers that weighing had shown, but the drives and tags are listed as 80psi psi which is lower than weight on those positions indicate.

We don’t carry anything heavy in the coach so found it interesting that weighing all six wheels resulted in higher air pressures than the converter estimated at that time. The placard did not indicate how they estimated tire pressure - full/empty tanks, bays, etc. Anybody know how they determined air pressure for that placard?

Jerry

[Gil_J]

Those factory and converter placards should both be the same and based on rated axle weights. FWIW, some coaches exceed the Prevost's rated maximum axle weight. Yep, even some new ones.

With actual wheel position weights on a loaded as used coach, you can adjust the pressures.