I would like to know what is the largest size tire I can replace on my stock 99 4x4. I currently have the oem 255/70/16.

Thanks

 

You need to determine what you want to do with your truck. Changing tire size will affect it in many different ways.

Do you tow? Do you 4 wheel? Do you want to re-gear? Just want it for looks?

Physically, I've seen posts that say you can put on 285/75/16's (32.8" tall) without any modification. But it will effect your speedo and make the truck seem "sluggish" off the line. This is because it'll change your rear end ratio.

Some say that's it's ok, but other's say it's too tall. Just depends on what you want from your truck.

I personally have 265/75/16's (31.6" tall) on the stock wheels and suspension. It changed the speedo, but I fixed that. Not a major difference in off the line performance, but I've added an aftermarket exhaust and K&N air filter, so that helped some. I also have the 5.4l engine, so it has a bit more torque at lower rpm's then the 4.6l.

 

There are some guys here that have gone as big as 305's.

Now that's a big tire.

 

I know you are probably looking for a 33 inch tire, which would fit fine on your truck, but I just spent 700 bucks on some michelin XCX/APTs. They are also called Michelin LTX/ AT at some stores. Unfortunatley, they do not make them in a 33 inch size, at least not to my knowledge. This tire would be the same diamater as the 4x4 Off Road Package tires, but with a 16 inch rim. My tires are 31.8 inches so basically a 32. We just had 14 inches of rain and I went offroading, they are awsome! I also have two wheel drive. In the wet weather, its like having my old tires in dry weather, they are incredibly smooth. Another good choice would be a 265/75/16 BFgoodrich A/Ts or some 285/75/16 BFG a/ts.
Good luck on finding the right size.

P.S. I didn't notice any performance lost or shift point error, even though there shoud be. I also have a v6, so a v8 would be better.