I have an 86 F150 2WD with 3.55 gears, and wondered if the 3.55 gears would turn 31 inch tires? I think it'll do fine but a couple people on another forum said that I would need to regear.

 

Those other people are full of crap. Re-gearing only becomes an issue with big tires and numerically lower gears. 33" and 3.08 would be a problem. 31" tires and 3.55s would give you the same performance as 3.31 gears would with the stock 29" tires, in other words just fine. In 86 I'm pretty sure that 31" were a factory option.

You will need to change your speedometer gear though but somehow I don't think that's what they meant

Tell us what other forum so we don't waste our time there.

 

yea, i have 31x10.50's on my truck with the stock 3.55 gears and it moves perfectly fine.

 

ditto...

 

I'm running 3.08s & 33s right now with no problems. Even with a little 4.9L pushing a 4WD thru a 4sp (but 1st is a granny, so it's more like a 3sp) and towing/hauling ridiculous loads cross-country.

 

im running 35's on stock gears... no problems but im going to regear when i sas