my truck isin the shop getting some new wheels with bfg at's. im kinda confused about tire pressure when going with non oem tire sizes. ill be going up from 275/65/18 to 305/65/18. some people i know with bfg's run them at max tire pressure(65psi) while other people tell me to run them oem(40psi). who is right in this matter? is ther any kind of formula or any good guidelines to calculate correct tire pressure?

 

65 is too much. 40 is a bit too low. As 65 is the max, whether they are Load range D or E, 45 would be right.

 

I just had my BFG 305/65/18's put on (load range E) and the tire shop put them at 45psi.

 

I agree 45psi should be enough for everyday use.

 

I've always used 40 psi for daily driving. If you tow/haul, you will want to go higher. A lot depends on how you use the truck, but the max psi listed on the sidewall is too high unless you tow/haul something really heavy every single day.

 

40 is what I would run.