Just got my Toyo MT 33x12.5x18 mounted to my factory 18" 5 spoke wheels on my '08 scab. The installer set the tires at 35 psi, the factory recommended for the oem tires. The M/Ts are a max 65 psi, so am I running 30 psi too low for these tires? What is everyone with these tires running for pressure? If I bring it up some, to say 45 or 50, will that put my tpms on the fritz or does it only come on for low pressure? I know higher pressure will be a harsher ride, but if it means longer life from these, at $1500, I'd like to keep them a while.

 

Those are a LR E, max pressure 65, and a load rating of 2600lbs at 65 (a bit low for a LR E). Since the load rating is that low, I would run them at 50, and would not go any lower than that.
35 is way too low and could be dangerous. Normally I would have suggested 45, but with that weight rating 50 will be better. You want the tires to handle at least your axle rating which is 4000lbs. 50 will give you that.

 

I'd probably start at 50 and check your tread wear then adjust the pressure accordingly.

 

Thanks guys, I brought it to 50, seems a little stiffer but not all that bad. The only thing I can think of is they put it to factory spec at 35 for the truck's oem tires, not thinking about it being a different tire/load rating/size, or they put it to 35 because it's a 12.50 squeezed on the stock 7.5 wide wheel (pretty sure the chrome clad 5 spoke xlt 18s ar 7.5 wide) so the center/cap of the tread wouldn't crown and wear too quickly. The sidewall is pulled in some to the rim, but it's nothing drastic, actually looks kinda good, and at 35psi, the center of the tread wasn't higher than the outer edge, and at 50 psi, i didn't notice anything worse. I gotta throw a level on it and see if it's flat across. Thanks again.

 

My Trail Grapplers are a load range E, started out at 50 and center tread was a little higher than I like (unloaded of course), moved down to 45 and I like that better.