i know someone has have had to ask this question. i just cant seem to find an answer.  i have a 2000 tj 4 banger. i have 31x12.5 pro comp muds now. but i wanna go higher in tire size. what tire size can i use. i have a rubicon express superflex 3.5 lift. can i go to 33's? how much trouble will i have on the road just trying to push these tires?

any info would be worth wild.

thanks.
j  

It depends if your in a hurry and if you live in a mountain area. In the flats it will do OK but your Jeep would be much more of a performer with some 4.88 gears to match the 33s.  

It depends on the weight of the tire/wheel combo and how extreme the tread is.

Example:  I lived in Central NJ, and ran 31x10.5 R15 ProComp Muds and was happy with my Jeep.  I put a set of 33x12.5 R15s on it with the same rims and it was a dog.  I could barely use 5th gear.  Central NJ is relatively flat.

The Jeep in question is a '94 YJ with the 4-popper and the manual AX-5, but the running gear is largely the same, as is the motor.

Same Jeep in Southern California, while not mountainous, is definately more hilly, the 4.10 gears with the 31s were still ok, but the Jeep could've used more gearing.  With 33 inch Mickey Thompson MTZs on it, my mileage went down under 10, and I was in third as much as 4th (5th happened only with a good tailwind).  I put 5.13s in it and it is better, mileage is still only around 14 though (until I climb any hills on the freeway, and then it plummets).

I guess the quick answer is, I wish I left the 31s on the Jeep, maybe some skinnny 32s would be ok.  Even with the gearing, I think the 33s are too much tire for the 4-cylinder, unless you are in really flat country.  

Just like those two said, make sure you gear it for whatever you do.  

I'm running 245x75x16 (31s) on my stock 04 TJ 4 cyl. While performance is OK the mileage has plummeted. Will regearing increase my fuel economy or jut increase performance. Any suggested gear ratio?
Thanks,
Dennis  

regearing will get the cruise rpm back up where it was, so yes on both counts.  

You may be getting better milage than you think. With the bigger tires your speedo is spinning slower. Did you compensate for this when checking milage? If the stock tires were 27-inches then you increased tire size by 15% by going to 31s. Meaning your milage is 15% further than what the speedo is currently reading. Meaning your gas milage is 15% better than you thought. Unless you swapped out the speedo gear for the correct one when you changed tires.

Figure out what size the stock tires were and do the math!  

I currently run 35inch procomp Xterrain with RE superflex 3.5 inch suspension lift with 1 inch body lift. Its in my mind the perfect amount of lift, no rubbing with stock flares. If you go to wider flares than it will rub the flares. This was something I did not relize before buying the oversized/wider  flares. Prior to regearing it was 4th gear with 33 inch tires and I live at sea level. Now its better, but not great with 4.88. With 33 you will not need the body lift, your gas milage will be great without regearing( I got about 20mpg with 4.10 and 33, but its pretty doggy. Your gas milage will not get better with deeper gears!!  

I neeeeeeeed some of whatever your smokin. LOL, I ran 33's on 4:10's best it would do is about 10.5 and was more guttless than a 4 banger, switched to 4:88's when the tires wore out went to 34's then we start to see about 14-15 on the hwy if I hold my chin just right. well, ok at sea level, flat ground and never over 50mph, maybe? the gears do help the mileage and masively helps restore the power back to a pre lifted condition not to mention saves the clutch, did any body else read willy's post? It has similar results as mine. mine however is a 4.0
jeep even claimed higher mileage for in town driving with the tj rubicon's 4:10's vs the tj wrangler models with higer gears.  

i know it is off subject but how did those mtz's hold up???? how many miles did u get out of them  

I'm in a similar position, I just recently lifted a 2000 TJ 2.5L with a 4.5" RE Superflex lift.

I currently am running BF Goodrich All-Terrain 31x10.5 15 and I personaly feel that the jeep is a dog with just those tires & stock gearing.

I'd like to run 35's with that lift.  Would 4.88 move the 35s ok?

And will 35s fit with the 4.5" RE lift?  I installed the supplied Bumpstop extenders which add 1 & 1/2" inches to the bumpstops  i just don't want to wreck my fenders just yet =) .  

4.88'll be ok for 33-35"
i'd run 5.13's though if ya could get em for the d30/d35 axles.

yep the 35's will fit, you may need another 3/4" longer bumpstops.  

Definitely need more than 1.5" of bump stop extension for 35's. I'd say at least 2.5" in rear and 3.5" in front. Remember, if your using the stock bump stop bumpers they compress another inch after they make contact.  

really unless ya unhook the swaybar the front suspension won't even flex enough to let the front tires get in the fenders, if yer jumping it they may rub but won't hurt anything...  

Probably true. I determined my bump stop length with no sway bar, no springs, and 315/75/16 (34.75") on 8" rims with 4.7" of backspacing. Real easy to get full compression and full articulation with the springs out.