I have a 2000 Xterra SE 4x4 currently with 265/70/15s on it. I want to go bigger on the tires and I am trying to figure out what will fit without having to lift it or worry about rubbing. I am looking at getting the BF Goodrich TA-KOs. When I was just sticking with the 15s everyone at the shop said the largest I should go with is 30/950/15s.I am now looking at bigger wheels as well. Thinkng 17 or 18 ?? Any ideas ???

If you're gonna be offroading, then definitely stay with the 15's. I'd probably go to a 265/75/r15, which is basically a 31" tire.

The problem with larger rims offroad is that for a given diameter, you have less sidewall height. This means that the tire is basically less flexible, and will not conform well to the terrain, causing you to loose traction, and also to have a rougher ride.

Thanks Anthony. Ya I've decided to stick with the steel stock 15s. Plus it will save money for other mods. I've am confused how the tire size numbers are derived at, for example how a 265/75/r15 is a 31" tire?? Will 31s fit a 4x4 SE without having a BL or worrying about rubbing?? So far I am looking at the BF Goodrich TA/KO in size 30/950/15. Thanks again for the advice.Already been a big help.

I'm not sure what you mean by 30/950/15 ??

Tire size is broken down to three parts... width/sidewall/rim

Width is given in Millimeters, Sidewall is a percentage of the width, and rim inches

So for example we'll say 265/75/15

Width = 265mm (about 10.43inches)
Sidewall = 75% of width = 198.75mm (about 7.8inches)
Rim = 15 inches

So if we add the rim diameter + sidewall(x2)

(15) + 2*(7.8) = 30.6 inches

This is probably the largest tire you can fit without major trimming or a BL. You probably just have to shave the plastic where the mudflaps were mounted (I assume you've removed the mudflaps)