I have a 1999 explorer 4.0 ohv v6, with p235/75r15 tires on 15*7 rims. need to know largest tire that will fit and stay stock?

Safely, I'd say 30x10.50s

30x9.50's fit easy and 31x10.50's fit on a lot of explorer's. Depends on how much your suspension has settled.

what do you mean if your suspension has settled? are you saying they might rub? i was going to eventually get 31's too, but i don't want to change suspension, no lifts or anything.

Thanks for the info. also my rear suspension sits a little lower than the front. anything simple to level it out?

there 3 options:

1)shackles
2)add-a-leafs
3)lower the front torsion bar to make it level but since you want larger tires i'd do options 1 or 2 or do both.