Cold tire pressure?

[DQDick]

Since we were leaving Albuquerque headed for the middle of Oklahoma I checked the tire pressure yesterday afternoon when the ambient temperature was 70 degrees (OK temps were to be in the 80's today). All the pressures were near 110#. This morning when we left it was 48 degrees and the pressures were around 102#. Once we got moving the tires went up to their usual pressure of around 125# and stayed there. Now that we are parked for the night the temps are in the 70's and the pressures are near 110# again. How do you judge cold tire pressure when you are in the desert temperature extremes or going up and down the mountains or both?

[Crossthread]

If they are all within a couple pounds each time you check them in the morning, I'd not worry about it. Temp and altitude varies. Bill

[catskiner]

I check them just before the sun comes up and write each tire pressure down and then go back to bed. When I get up much later I check them again and add or lower the difference.

[pineranch]

I go from 35' to 7500' and never adjust but monitor for leaks.
Mike

[JandC]

Dick I had the same question. I had exactly 105 pounds in each tire prior to leaving Ft. Myers. Checked them the air compressor, high end tire gauge, and TMS. All tires were in the shade and outside temp was around 75 degrees. The highest reading I got driving back north was around 118. Had a cold morning starting out in southern Illinois (around 45 degrees) and they were all at 96 pounds. I just didn't think they would change that much.

[jcurtis934]

I guess the real question is: what do the tire engineers do? In 'jandc's case, 9 lb over 30F temp change really isn't all that much (pressure prior to travel). If one were towing the rig in 45F temps, i think you would set the tire pressure at 105# before starting the tow and keep tabs on it every day or once a week. Air changes its density with temperature and altitude. My headset has always been to adjust the tires before travel to reflect the psi for the load rating. Now that i am running load range h tires, i have very little to worry about since the range is very broad. In other words for my tires, they support 3375 lbs at 75 psi and 4805 at 125 psi. Hard for altitude or ambient air temps to get me anywhere near not safely support the monty. I initially set my tires to 105 psi which supports 4225 lbs...and that is what i keep tabs on when i am on the road. John