The Jeep Wrangler JK comes from the manufacturer with various tire sizes depending on the model Wrangler you buy: Rubicon, Sahara, Sport etc. The stock tire sizes are: 255/75R17 (32"x10"), 225/75R16 (29"x9") and 255/70R18 (32"x10").
Backspacing determines how far the wheel and tire will stick outside or inside the fender. The stock wheel backspacing for every late model Jeep Wrangler JK is 6.25". If your wheel backspacing is a smaller number like 3.5" then the wheel will have a wider stance and the tire will stick outside the fender more than normal. This would be considered a "deep dish wheel". As we know, the stock Jeep backspacing keeps the factory tires sitting just inside the fenders.
Most people will tell you that the largest tire diameter you can run on a stock Jeep JK is 33" and this is true... on the street. But, if you intend to tackle rougher terrain where there will be more articulation (flex), you run the risk of your new tires hitting and possibly damaging your fenders.
If you are going to run a 33" tire on a stock wheel, you will have the least amount of problem with a 33" x 10" tire, even off-road. In many cases, even a 33" x 11" tire on the stock wheels can be used without a problem. If you've installed a larger set of tires and you experience rubbing on the front sway bar, frame rail and/or lower control arms while making full turns, the best and only solution in our opinion would be to install a set of wheels that have the correct amount of back spacing. Some tire shops may suggest that you alter the steering stops or add wheel spacers to eliminate the rubbing. You should always avoid these shortcuts. Why add an extra measure of mechanical complexity and possible failure points to an area of your vehicle that is already a very dynamic point?
Here are the most common tire sizes that measure 33" x 11":
285/75/16,
285/70/17
275/70/18.
If you want to run a tire wider than 11", here are your choices:
295/70R17 (33"x11.6")
305/60R17 (33"x12")
305/70R16 (33"x12")
295/65R18 (33"x11.6")
you will need a set of aftermarket wheels with 4.5" backspacing or less.
One thing to keep in mind when adding a taller tire is that your Jeep is going to sit higher. Therefore your center of gravity is higher, and as a result you will have less stability. We advise that if you go higher, you should also go wider to compensate. It will handle better with a wider stance, and most people think it also looks much better.
If you intend to hit the trails on a regular basis, you would be well advised to stay with a 17" wheel.