General Info
You can fit tires up to 31×10.5 inches on a stock TJ without buying a lift kit. The stock YJ can only fit tires up to 30×9.5 inches. When you put larger tires than stock on a vehicle, you'll be slowing the engine down and losing some power. This may be a concern if you are thinking about putting 31” tires on a 4 cylinder TJ, but I have a friend who has done this and doesn't worry about it too much.
If you have the stock 6 inch wheels, you're limited in what you can mount. You can mount up to a P235/75R15 tire on these wheels, but this might be pushing it. Try to get the 7 inch wheels, if at all possible. Or, drive directly to a tire dealer after buying your Jeep and trade in the stock tires and wheels on something more off-road worthy.
If you get aftermarket wheels, make sure they have the correct offset. Wheels that stick too far beyond the sides of the vehicle, while they may look cool to some people, can put additional stress on your wheel bearings. Ask your Jeep dealer's parts department about this.
The Fall 1996 issue of Jp magazine has a fairly comprehensive guide to tires made by different manufacturers, but they don't provide test data or recommendations. The kind of tire you need depends on the type of off-roading you do and the terrain you plan to encounter.
If you put 31” tires on the stock 7 inch wheels, you may experience rubbing on the control arms when you turn the steering wheel all the way in one direction. You may need to adjust the steering bump stops to compensate for this.
Teraflex
KIT: Stock 5.5” wheel– 8” wheel with (3-4” backspacing)– 10” wheel (4” backspacing)
BB1T (sw): 31×10.5– 31×10.5– 31×10.5
BB1Z (sw): 30×9.50– 30×9.50– 30×9.50
BB1X (sw): 30×9.50– 30×9.50– 30×9.50
BB2W (sw): 265/70R16– N/A– N/A
2T (sw): 31×10.5– 32×11.50– 32×11.50
3T/ S3T: 33×9.50– 33×12.50– 33×12.50
3Z/ S3Z: 30.9.50– 31×10.50– 31×10.50
S4T: 33×9.50– 35×12.50– 35×12.50
S4W ®: 265/75R16– 265/75R16– 265/75R16–
S6X: 33×9.50– 32×11.50– 32×11.50
(sw) Sway bars connected
® May require slight modification to prevent rubbing
Rubicon Express
* TJ 2” kit: 31×10.5” tires
Skyjacker
ARB/Old Man Emu
Rancho
Superlift
4” lift system: Tire sizes not listed, but the page shows a vehicle with 33” tires; another catalog I have shows this kit with a 2” body lift and 35” tires
1.75” lift: Tire sizes not listed
Trail Master
Recommended lifts for the YJ according to: http://www.off-road.com/jeep/2001/TechWhatFits.html (they say that TJ's May use up to 1” larger tire on street)
30” tires
No lift required - however small lifts will increase articulation greatly
No lift required - however a 1” or 2” body lift could be used to increase articulation
No fender trimming required and none recommended
31” tires
No lift required for street use but there may be some slight plastic fender rubbing. 2” to 3” lifts are recommended for trail use to increase articulation
No lift is required but a 1” or 2” body lift can be used in place of a suspension lift to gain clearance and eliminate rubbing
No fender trimming is required and none is recommended
32” tires
A 2” to 3” lift would be recommended, a 4” lift would provide greatly increased articulation without rubbing
A 2” body lift combined with 1” lift extended shackles could be used to clear this size on an extreme budget.
With extended shackles or small suspension lifts there may be some rubbing at the corners of the plastic fenders under extreme conditions.
33” tires
A 4” suspension lift or spring over conversion is recommended.
A 1” or 2” body lift is recommended to increase clearance
Some rubbing may occur Some trimming of the bottom trailing edge of the rear fender may be useful.
35” tires
A 4” suspension lift or spring over conversion is necessary. Axle & brake upgrades are highly recommended as well.
A 2” body lift is recommended, a 3” lift can increase clearance.
With a 2” body lift trimming some fender edges as much as 1” or 2” may be needed.