80 is gunna give you a really hard ride. i woulld run them around 65 or 70. anthing lower will cause uneven wear and poor gas mileage. my offroad tires max out at 65 and i run mine at 55 or 60. depends on if im hauling something or not.
What you really should do is draw a line across the full tread width of the tire with chalk. Drive a short distance, then check to see that the chalk wore off evenly across the tread. You want an even footprint. If the edges wore off and the center remains, you are under inflated. If the center wore off and the edges remain, you are over inflated. I'd suspect a psi of more like 40-50 to be correct. My coopers say 60 psi max I believe(may actually be 80, don't remember) and I run them at 45-50 in the front and 40-45 in the rear, that's what works by the chalk method.
On the 2500's the tire pressure mont. system light will go off at around 60psi I think. My E rated tires say 80psi max too and I run them at around 63-68lbs to get a better ride and to keep that darn light off. But chalk is the way to go for on road riding. Off road U can lower them into the teens to gain better floatation in sand, rocks, mud. Just reinflate when back on the road. If dropping into the low teens often I'd consider beadlock rims to avoid breaking the bead off the rim.
ive never heard of the chalk line thing but that sounds like a good idea. i dont have the tire pressure light thing but i work at an oil change so i always make sure my tires are inflated properly. i do a bit of hauling every week so my tires stay pretty high but even when i go off road i just leave them where they are. unless i go up to silver lake sand dunes then they get aired down to about 15 psi all the way around. i might actually try that chaul line thing here in a week or so when i rotate my tires.
I believe the pressure marked on the side of the tire is there to tell you to never go over that point
I believe it is the point where there could be damage to the steel radial bands, if that pressure is exceeded.
As was mentioned, the load of the vehicle determines the amount of air that should be run in a tire
Our Rams weight is close to 5,500 pounds, divide that by 4 tires = 1375 pounds per tire, then allow for the weight of the engine & transmission & adjust accordingly
Goodyear Wrangler 275/60R20 LT Maximum Load 2601 Lbs
Max tire inflation 44 PSI
HOLY CRAP, 4 tires like these could hold 10,404 Lbs
I run mine at 35, which is what the door says... I never heard of doing the chalk thing but I might. After reading what everyone had theirs set at I put 40psi in each tire... rides like a brick now, maybe my new shocks will compensate a bit for it when I get them in but for now I am sticking to 35 psi
so i tried the chalk line thing and i was pretty much spot on psi. i checked my tires before i made the line and they were sitting at 55psi. i also did it again and dropped the pressure down to 45psi. when i did that the only thing that wore off was the inside and outside edge of the tires. so i bumped em back up to 55psi and im gonna leave em there. now a co worker of mine did the same thing and he also has 65psi max tires and found the best psi to run in his truck was some where 40-45 psi. i have come to the conclusion that depending on the make of the tire, the compound its made from and the weight of the truck depends on the psi you should run in your truck. i will defiantly be passing this info on to alot of friends and anybody who asks what psi they should run in their tires.