Community Forums

woodosgood · 10-09-2018, 02:44 PM

We have traveled from Maine to Georgia in the last week and had to adjust the tire pressure as the morning lows have increased as we head south. This is just a reminder to everyone who may be traveling at this time of year to make sure you check your tire pressures and add or remove air to make sure they are at the desired “cold” tire pressure.

Stump Jumper · 10-09-2018, 02:47 PM

I have checked mine cold and after travel and it is surprising how much the pressure varies just due to heat.

Old-Biscuit · 10-09-2018, 03:01 PM

Should be part of routine when getting ready to travel......check/adjust tires in AM

tvp · 10-09-2018, 03:49 PM

So if your Cold tire pressure is supposed to be set let's say at 85 Lbs, and while driving it goes up to 95 or 100 psi should I start at 75 lbs ......knowing it will increase as I drive ?

Bobj616 · 10-09-2018, 04:03 PM

The pressure stamped on the tire is the recommended COLD tire pressure . The manufacturers know the tire will heat up as you drive.

woodosgood · 10-09-2018, 04:19 PM

There are several good discussions on IRV2 about the right tire pressure for your particular rig, but the short answer (for me anyway) is to weigh your coach on all 4 or 6 corners, determine the tire pressure for that size tire and weight from the tire manufacturers chart and make sure your tires are at that pressure before you start driving each day. Check the pressure before the sun hits the tires and warms them up. The temperature later that day does not matter.

THenman · 10-09-2018, 04:23 PM

Quote:

Originally Posted by tvp

So if your Cold tire pressure is supposed to be set let's say at 85 Lbs, and while driving it goes up to 95 or 100 psi should I start at 75 lbs ......knowing it will increase as I drive ?

NO !!

Get your cold pressure from tire mfg and weights for your coach from scale.

You can run for full load but will get much better ride at proper pressure for your loading. Axles should be set same for all tires on them at pressure recommend for max weight of your load on that axle.

Tom

Stuart W · 10-09-2018, 04:28 PM

As said, cold pressure is just that, weigh your coach and refer to the manufacturer tire chart for the correct cold pressure of your tires, use that number no matter what the ambient cold temperature is.

Roameo · 10-09-2018, 04:39 PM

Quote:

Originally Posted by tvp

So if your Cold tire pressure is supposed to be set let's say at 85 Lbs, and while driving it goes up to 95 or 100 psi should I start at 75 lbs ......knowing it will increase as I drive ?

No. The pressure listed on the sidewall of your tires is the MINIMUM pressure that your tires need to be set at in order for them to properly carry the maximum weight of your RV, and this pressure should be measured "cold"; that is, BEFORE you begin driving for the day, or after they've had sufficient time to cool to ambient air temperature.
Don't worry about how much pressure they expand to as they warm up. As a professional truck driver, my COLD tire pressure is set to 110 psi. After 600-700 miles of driving for the day they'll often measure 120-125 psi. These pressure readings aren't anywhere near dangerous levels. Generally speaking, your rims will fail at extreme pressures before your tires do.
The number one cause of tire failure is due to UNDER inflation. Thus, in your original question/example, setting your cold pressure to 75 would be detrimental to the structural integrity of your tires (causing them to both overheat AND not be at a sufficient psi to carry the weight of your RV) and, quite possibly, could lead to tire failure (a blowout).

- Joe

hohenwald48 · 10-09-2018, 05:06 PM

Quote:

Originally Posted by Roameo

No. The pressure listed on the sidewall of your tires is the MINIMUM pressure that your tires need to be set at in order for them to properly carry the maximum weight of your RV,

Actually, the weight rating of the tires and the maximum weight of the RV are not necessarily related in any way. I've seen many RV's with less tire than RV.

Roameo · 10-09-2018, 05:14 PM

Quote:

Originally Posted by hohenwald48

Actually, the weight rating of the tires and the maximum weight of the RV are not necessarily related in any way. I've seen many RV's with less tire than RV.

Yes, you're correct in that the tire weight rating class doesn't necessarily correspond to the weight of the RV, although the weight class on the tires SHOULD be of a significant rating to handle the RV weight and speeds at which it will travel.
Here, I was merely trying to say that the PSI listed on the tire's sidewall is the MINIMUM cold PSI at which the tire needs to be inflated to in order for it to perform properly at the maximum weight rating of the tire itself.
Hope this was a bit more clear; apologies for any confusion.

jbikes1 · 10-09-2018, 07:20 PM

The question is I get up in Texas and the temp is 33 but I am traveling into 85 degrees......is the difference between cold 33 and cold 85 enough to worry about. Anyone know how many pounds I would gain with that 50 + degree change. Im guessing it could be upwards 15 degrees which seems like something to worry about?

TJ · 10-09-2018, 07:33 PM

We stop every 100 miles, let the tires cool to ambient temperature, adjust the pressure and get back on the road for another 100 miles.

I think this is being overthought! Set/check your tire pressure in the morning before the sun has warmed the tires and drive. This is NOT a situation where a tire properly inflated at 50 degrees will blow up in 80-degree temperatures. All this has been considered in the engineering of the tire and rim.

EDIT: Just did a little research and the generally-accepted rule for tire pressure increase due to temperature is .8 pounds per 10 degrees. Let's call it one full degree. An 80-degree change in temperature will result in a change of 8 psi...actually, a bit less if we go by the generally-accepted standard. Not enough to worry about...except, possibly, when the temperature decreases 80 degrees. Then, your tire might be just a shade on the low side if you run them at minimum pressure for loading.

TJ

Roameo · 10-09-2018, 07:38 PM

Quote:

Originally Posted by jbikes1

The question is I get up in Texas and the temp is 33 but I am traveling into 85 degrees......is the difference between cold 33 and cold 85 enough to worry about. Anyone know how many pounds I would gain with that 50 + degree change. Im guessing it could be upwards 15 degrees which seems like something to worry about?

No need to worry. Begin each day with the proper tire pressure - no matter the outside air temperature - and all will be fine. Tires are more likely to fail due to under-inflation than over-inflation.
With over two-million miles of driving, I've never heard of a tire failure due to over-inflation, but I see under-inflated failures (think shredded tires left on the highway; aka gators) every day.