I have a 92 Ford F150 4x4 5.0L 302 V8 with a AOD transmission. It has a 3.55 gear rear end, it came stock with 235/75 R15 tires. I have been told the biggest i can go on a 3.55 rearend is a 29x10.50 tire. I want to know how big i can go without re gearing. 33x12.50 are way to big and has made me have transmission issues which have been worked out. Id really like to know if there will be a problem with a 31x10.50 R15 or R16 Tire? Because is slim pickings on a 29x10.50 and i dont want to stay stock tire size.

 

31's will be OK. I have never seen a 29x10.5 tire but 30x9.5 was common.

 

You won't have any problems with 31x10.50's. Only 2in bigger than the 235/75's.

 

I have a bronco with 31s and that setup it worked fine for me

 

Ran 33x12.50 on a 90 bronco for years with 3.55 gear. Truck did not live an easy life, ran the snot out of it, the occasional burn out, towed a 4500 boat, lightly wheeled it, drug large trees out of the woods, I even pulled a bunch of pine stumps out of the ground. Never had an issue other than having to get the rear driveshaft rebuilt and stripping the factory hubs. I did have the 351 and a tranny cooler. Truck had 205k when I sold it and ran like a top. Wish I had it back. I did take it out of overdrive when towing. I can't see you having issues with a 31x10,50. Go to Randy's ring and pinion and use their calculator. These trucks came with 3.08 from the factory and I don't believe a 31x10.50 will put your gearing higher than that. Remember, sometimes things just break.