The stock tires of my 2001 F150 still look flat. There Bridgestone 255/70/17 but even though I have about 36 lbs in each one, they still look flat. The max is 44 lbs and I dont do any towing besides carrying a fourwheeler. How close can I get to 44 lbs and it still be safe?

 

You can go to 44. However, you will get no more load carrying ability with that pressure. A p series tire has it's max load carrying ability at 35. Anything over just helps with sidewall flex. Don't know if at 44 you will get fewer miles out of the tread wear. Another option would be to go to an LT tire. A LR C with a max of 50 would be run at 36-38 on your truck. Other LR tires would be different pressures.