Hey I was wondering that the biggest tires that would fit on a 1990 F150 2wd stock ones are 235-75 r15

 

I have 31x10.5x 15 general grabber at2's on my 94 f150 4x4. I have heard of 32's being put on but may have some rubbing issues? If you are looking for a good all around tire i recommend the grabbers. quiet on the road, excellent in ice and snow, performs very well in the mud also at a reasonable price. i had all 4 mounted and balanced on my stock wheels cost me 574.00 . Best investment i have made for this pickup bye far. Just ask my girlfriends brother, my f150 just pulled out his 89 chevy thatwas buried too the frame, has 33x12's and a worked 400 small block in it. not too mention the chevy didnt help at all!! if your looking for just a straight up mud tire and money is not an issue check out dick cepek tires, very aggressive also bf goodrich has good mud tires, honestly I would take my grabbers over any of the above because of their versatilityand low cost. excellent tread wear also

 

I got 31x10.5x15 BFG AT's on my 96

 

Are you looking for tallest or widest. The tallest I believe is 31 inch for the two by, widest depends on if you want to tub or put hips on the bed.