What PSI should i run my new tires at?

Just put on Cooper Discover ST Maxx 285/75/16 with 16x8.5 level 8 guardians. tires are load range E on my truck and they're a lot stiffer than i thought they would be. My truck bucks over the smallest bumps and louisiana roads are shit, so its noticeable. im taking the truck in tomorrow to get everything aligned because i put the wheels and tires on myself and i think this may have something to do with it. Should i just air down a little bit to soften things up or could it be my alignment? on smooth pavement it drives and rides like a dream, doesnt pull to one side, steering wheel doesnt shake, and the truck takes corners like a beast. any advice?

 

search for the chalk line procedure to set your tire pressure in these forums.
285's will rub in turns without cutting out material.
As far as being a stiffer ride than the other tires, I'm not sure why.

 

x2 on the chalk line test.............google it

trucks vary in weight depending on 4 door, reg cab, access cab, bed length, 2 or 4wd, tool boxes, armor, etc.

I will say.......... dont run em at the MAX rate on the sidewall unless ur at max capacity and its warranted.

and dont run them at the psi in the door jamb because thats for the stock tires and may be too low.

too much air causes a rough ride, early tread wear on only the center tread area, and smaller footprint.

too little air causes excessive tread wear on the outer portions of the tread face, sloppy turning due to sidewall flex, increased tire pressure due to the sidewalls having less support from the internal pressure and can cause a blowout (they support the weight, not the tread face), poor MPG (it is a truck tho), etc.

 

I run 35psi on my BFGs 285/75/16. Smooth ride. And americas tire set it there. Im sure they know what they're doing.

 

Uhh shouldn't you follow the door jam sticker and then worry about drawing chalk lines?