tires are general there is no read out on the tire that says use this PSI for a ranger/jeep/f-250. the MAX psi labeled on a tire is just that MAX.. you shouldnt exceed that it doesnt mean fill to that point and your good to go..

the PSI on the door/fuel door depending is a # derived by a calculation from the tires that come stock on the vehical what PSI SHOULD be run in the truck for THOSE tires...

see tires have something labeled on them that reads like this... "tire can support 2500lb at 55 PSI MAX".. now say you drive a reg cab 4cyl ranger which weights right around that amount. that means that 1 tire can support the WHOLE vehical weight at 55PSI... there is a calculation, i cant remeber it for the life of me but taking effect the vehical weight with how much the tire can hold at a curtian psi you will get what psi the vehical should be running. i found it once worked out my truck with my old 265 and came out with right around 32psi...

so your statement of running what the tires says well its true and false, the tires do tell you what to do, but you have to do some figuring out.. if the guy is still running stock or a tire with a similar to stock load rating then he should run what is said on the doorjam/fuel door