So, I just got back from the annual desert rat Nevada desert ATV week that's been going on for me and my buddy for 22 years (the trip, not the ATV part). I've decided I like about 4 pounds of air in my tires. I check them every morning. We'd leave about 8am, still chilly out. By noon it's into the 80's and by later in the afternoon it's up into the 90's. Just for grins I check the air in one of my tires and it's up to 8-9 pounds! I'm guessing this is because of the heat. Or is it the altitude change (which could change as much as 2-3000 feet in the course of our 'adventures'). Or is it the heat buildup from the simple act of tires rolling on the ground? Or all the above? And so the question is, should I be adjusting the pressure all the time if I want the favored 4 pounds of air in the tires? During a coupld of 'assaults' on steep, gravel laden hills I'm sure I would have had an easier time of it if I'd had less air in the tires than had built up over the course of the day. But constantly adjusting air pressure is a pain in the $@& and would take the fun out of riding.

Then, the following morning when I 'd check the tires, there was actually more air in the tires then the previous morning when I added or let out air to get me back my beloved 4 pounds. GASP!!!

Any thoughts on this?

 

Mr Tommy, Weclome to the real world of tire pressures. The answer is all of the above. As to maintaining 4 psi, I would say it comes down to how much better does the 4 psi make the ride? Then the question is, "Is it worth jacking around with it to stay at 4 psi?" When I check my tires I like them cold. The pressure will rise with just riding due to tire flex, so if it is at 4 to start with and you stay at the same altitude and check the tires again it will be a bit higher. If you RON at a higher elevation and check the pressure the next morning, they will be higher. And as you say just ambiant air temp will raise them. I usually adjust mine, if I start at higher altitude. Otherwise I ignore the issue. Oh yeah, I also start at 4 psi, but on cool days know that it only raise about 1 psi from riding. Cool mornings, hot days have given as much as 3 psi increase and altitude changes make the biggest jumps. From my sea level to 5000 ft double the 4psi and it was 10 degrees colder that morning.

 

Thanks Bear. I figured I was in deep do-do, air pressure wise.

My wife and I will be back in the same area next week, only the temps are already getting chillier and I suspect there won't be as much of an up and down change. But, I may drop down to a 3 pound start and let it slip up to maybe 5 or so. The ride is a lot better at 4 than it was at 6, and for all I know, the 6 actually might have been 10-12 once we got going. No WONDER I had a rough ride! But the lower pressure sure makes the steep, rocky uphills easier.

"Johnson's Law": Everything is a hassle...[img]i/expressions/face-icon-small-wink.gif[/img]