So I've always known that the more tire (smaller the wheel), the better the off road performance but I've almost exclusively seen mud grapplers with larger (18"-22") wheels. Is there something to those tires that works better with a larger wheel? I'm looking at 37x13.5 mud grapplers as my next wheel and am a little thrown off with all the examples I've seen that go against the wheel size I was expecting to use (15"-17")

 

The wider the side wall the better, better ride on road and better traction offroad especially when you air down. The larger wheels will perform better as far as handling onroad, but that's not really where a Jeep shines. I'm currenly torn beween upgrading my 35s to 37s or 38s. My hesitation to go 38s is the 20" wheel that is required to run Nitto Trail Grapplers, I've been so pleased with my 35s and I don't want to change models.

 

You can run 17" rims without issues. They are no different then other tires in the same size.

They do make the tire in larger rim sizes as well because they are popular with the full size pickup truck crowd. Some of the 1 tons out there require larger rims to clear brakes. Also truck guys just like running huge rims with tires as well.

 

I was looking at the 38"s too but I decided to do 37"s because of the less need for improved steering assist (since 38s are also 2 inches wider as well)

 

if you think you won't need steering assist on 37's you're gonna have a bad time.

 

I agree.

 

I have 37s on 17 and I like them but I also have a psc hydro. But it will last awhile with out it but with lockers engaged its a pain to turn the wheels in a bind.