I just got ProComp's new Extreme A/Ts 265/75/16. The sidewall says 80psi max. I know you don't run them that high. What preassure would you run on the street?

 

i run 35 psi on my street tires...

 

i recommend one of two methods:

1. read the placard on your truck. psi is relative to weight at each axle. your truck isn't any heavier than when they made it right?

2. chalk test. draw some fat lines across your tread and air up/down til you have even wear across the line. easiest to do when over inflated first, then air down til scrubbed chalk gets wide enough for you

 

I run 35 on my claws, 30 was too low and it rode loose on the interstates here.

Sweet wheels, btw!

 

Yeah, but you've got a 2wd, and are probably not running D?-load rated tires. In fact you might even have passenger car tires. Its very much apples to oranges.

To the OP: I suggest you draw a line of chalk on the tire and play with the pressures until that line fades at an even rate across the tread of the tire. Its should have stiff sidewalls because it is a heavy duty tire and you might be able to run as low as 25psi.

 

i run between 40psi-45psi all the way around on my 31x10.50 procomp's!

they are rated for 80psi too!

i thought about running them at 80..to see how it would be..but i dont want to risk blowin a tire..

i ran my super swampers at 45psi all the time and never had any issues with them..

and so far my X-terrains are wearin GREAT! except for the driverside front...that pesky upper ball joint is bad..so its KINDA startin to show on the out side lugs..but no biggy..its gettin fixed soon!

 

That 80psi max on the sidewall of your tires also has a max weight per tire along with maybe a little more info. You are nowhere near that max weight that tire is rated for. If you do the math you can figure your weight per tire and lower that max pressure proportionally. That tire has got to have some beefy sidewall plys in there. Way overkill for your Toy but better over than under.

In my opinion, those tires, when aired down, won't flex and conform to different terrain as good as a lower load range tire would.

On the street, I usually run between 27 and 30 psi on my 32's or 33's. I get great tire wear and the ride doesn't require a kidney belt.

 

I run 35 in my cooper S/T's.
They're only 30x9.5's though.

 

the purpose of a specific air pressure in your tires is to maintain the load of the vehicle proportionately, while also maintaining the proper contact patch and sidewall flex. so regardless of tire size, your pressure will be dependent on the weight of the truck first, then the strength of the sidewall, which someone mentioned is D for this skin. the amount of pressure you'll need to keep the weight of the truck off the ground is fairly consistent, because the weight is a constant in the equation. (regardless of p235s or 33s, the truck weighs the same)

the strength of the sidewall will determine how much flex you get when you air down; how much load transfers from the air to the sidewall. if your sidewalls are too strong, your truck may not have enough weight to flex them and you could roll on very low psi with no side flex, but your tread would buckle in the center, so you're rolling on the edges of the tread. if sidewalls aren't strong enough, heat will build up faster and they'll break down quicker over time. cracking will result.

you have a tire that fits much bigger, heavier trucks, thus the need for a max psi of 80lbs. but your GAWR dictates the psi.

all that said, just roll at 32-35. good enough for full pressure and good mileage, but soft enough for driving over curbs easily when you need to make a shortcut.

 

general rule of thumb would be 32-35

I've seen people run 50 on a DD and never have issues, but eh, not me...



personally, I run all mine at 32, and I have on pretty much every vehicle I've owned, with 31's on my Toy, 33's on my old Jeep, the low profiles on my 18" rims on my old Isuzu lowrider, and the low profile performance tires on my 17"s I had on my Mustang; 32 has just seemed to be an all around good number

 

That's a little presumptious, isn't it? ... saying he might have passenger car tires? I don't have passenger car tires on my 91 2wd. What does the load rating have to do with being passenger or not? In a past life, I built smallish trailers (if you consider 40+ foot long RV's 'smallish') that used load range "C" tires, the tires were radials and the tires were rated all-terrain. So again, what are you getting at? We even offered "D" and "E" load rated, metric sized tires as upgrade options.

Or maybe you're suggesting that 'radials' aren't 'truck' tires? ... since you said something about stiff sidewalls? Well, if that's the case, "D" and "E" rated radials don't have stiff sidewalls like you're suggesting.

 

i run 35 on everything i own

 

Same here 35psi on all cars and trucks I own and have owned while on the street.

 

I run 29-30 psi

 

here's some more info to throw in the mix:
couple days ago i had a rotate and rebalance on my 33x10.5 BFG A/Ts with 4k miles on 'em. i got out of the truck this morning and noticed my tire track on the pavement (from a puddle) showed only about 6" of contact. 6" of a 10.5" wide tire. i checked the t.p. and it's about 40lbs. apparently they're used to putting 33s on heavier trucks, or are too lazy to check my manufacturer spec's.

tomorrow a.m. when it's cold, i will air down to 32 all around. should give me more tread to the pavement, and i like to jump curbs frequently, and don't carry much load/pass.

 

I don't bother with tire pressure, it's a myth anyways. As long as they look round and don't bounce too much on the speed bumps at the mall I'm not worried.

 

hahaha... i do believe they are radials though

 

30-35. Nice wheels!

 

the max psi number on the side of the tire is absolutely irrelevant. That has to do with tire inflation, not running psi. I spent all day today mounting and balancing tires. Run what your placard in your door opening says, or test out anywhere from 28-35psi. Most road vehicles short of semi's don't have any higher cold operating pressure than that. Oh, and just to be clear - when it says 'cold psi' it means when the tires are at ambient temp, not specifically cold in any way. If it's 90 degrees outside, the cold pressure would be measured at 90 degrees.

 

lol. 85 psi max. Reminds me of the time my future father-in-law was filling up my girlfriend's bike tire. Says something like 35 psi max. He gets it up to 25 psi and blows the tire up. Brand new bike too.