What are the offroad benefits of having a larger wheel?

 

Smoother ride
Larger footprint when aired down

The only thing is that SOME rims make contact with the brake pads and rotors.

 

To be clear, I'm questioning the diameter not the width. The way I understand it, and I know I could be wrong, is that the more rubber on the sidewall you have, the bigger the footprint you would have for floatation when you air down.

So the larger the diameter of the wheel- the less rubber on the sidewall. And from my experience with any kinda tire, the lower the profile, the stiffer the sidewall as well- meaning less flex. So for offroad vehicles what is the benefit of the larger diameter rim?

 

Not sure if I'm interpreting this correctly, but you're asking about the benefit of large rims, and less sidewall?

Ex: 33" tires with 20" rims.

It's going to be a more harsh ride, but it'll be less "floaty" I believe.

 

The tires for 15's are cheaper than tires for 17's.

 

A general rule is that the diameter of your rim must be half of the total diameter of your tire. For example 17inch rim 34-35inch tire. In that case you have enough sidewall but not too much. But in any case don't go beyond a 18inch rim in a JK, cause it's just wrong.

 

Any harm going to 35's with a 16 rim on?

 

Less "floaty" is exactly right. 35s feel very boatlike on a 15" wheel. In the olden days I would air the tires up past the max pressure to try to get rid of that feeling on my YJ (before I knew better).

 

The trend in wheels for Jeeps have followed the general trend for wheels for all vehicles. The practical reason wheels have gotten bigger in the past twenty years is to clear larger brake rotors and to allow for lower profile, high performance tires on passenger cars. This started with high performance sports cars and has trickled down to the general market where bigger is always better. Everyday passenger cars ride much better without the 20 inch wheels and stiff-sidewall 30 series tires.

The brake rotors on the JK are just large enough that the caliper will rub on most 15" wheels. Otherwise there's no real reason not to run them other than that isn't what is popular right now. Usually, the pricing of identical tires increases as the rim size goes up, and 15" tires are a lot cheaper than 17 or 18" tires for the same thing.

 

A lot of people including me run this combo.