termiteman

My jk is stock with 3.21 gears . I want bigger tires . I don't have a lot of extra cash, but would like to install some 33 inch tires . I know I may need 2 inch lift , rims, and/or spacers , but I don't want to regear. How much will taller, heavier tires slow my acceleration.

Lorrel

I'm sure some will say you'll be fine. As for me I got the wife an 07X auto with the 23S package. it came with 4.10's and the smaller SR245 x 16's, which are about 30.9" tires.
I doubt I'd be as happy with it were I to install 33's, much less, much less running it with 3.21's.

Adam3612

IMO 3.21's were too tall for the stock tires my jeep came with, forget 33's you're gonna notice it big time and want to re-gear. I went from P255/70/18 stock Bridgestone Duelers to LT 275/70/18 Goodyear Wrangler Duratracs and the difference was painfully noticeable on the highway (harder to get up to speed, harder to hold speed, passing becomes a bit of a task, shifting into 4th to get up inclines without having the pedal to the floor). FWIW I kept stock rims. no lift, just got 1.5" spidertrax spacers and the only rubbing afterwards was on the plastic air dam just slightly. 4.10's or even 4.56's are perfect for 33's on a 6 speed, if you have an auto you'll probably wanna do at least 4.56 if not 4.88.

Kastiron

I put 265/75-16's on my 3.21 geared unlimited 6 speed. It was ok on flat ground, but 6th gear wasn't used even in slight inclines or under 70+mph, even then it wouldn't hold cruise control.

I had planned to upgrade to 4.10 gears to regain sanity. Traded for the Rubicon before I got the gears swapped.

No way I would have enjoyed 3.21 and 33's.

termiteman

This helps me a lot. I'm running 255/75/17 wranglers , 6 speed, and 3.21s . The reason I asked this question was my jeep isn't very quick now, and I don't want too slow it any more. I think maybe ill stick with 255s . I guess that's near a 32 inch tire. I would like something wider and more aggressive. Any ideas on a good tire 32x11x17.

mostlystock

I had a 2010 JK 2-door, 6-speed with 3.21's, and tried it with 33's and 32's (same model: Cepek FC II) -- only a 4 lbs. difference per tire between the two sizes -- and I found a very noticeable difference in response / drive-ability. The 32's were okay but not great... I found the 33's very sluggish, so much that I ditched them and went with the 32's, even though I preferred the look of the 33's. 6th gear ended up being useless, and 5th was often useless. Had to stick to 1st through 4th. I did not like the result.

I don't recommend 33's with 3.21's, even on the 6-speed.

I think the 3.21's are best with 30" (like they do from the factory, with the 225/75R16's) on a 6-speed (on an auto, perhaps a little more sluggish, from what I hear). For 32, I think 4.10's are best on a 6-speed (auto, ditto above)
33, not sure, maybe 5.13

Yes you can probably get away with running a 2" larger diameter without changing axle gear ratios, but it'll be on the edge.

For 32's, I find the 4.10's perfect. Feels less sluggish, more power. Funny thing is... that's just how the factory did it. I think there's a reason for that!

The 32's were Cepek FC II 265/75r16
The 33's were Cepek FC II 285/75r16

With either 33 or 32, I highly recommend the TeraFlex leveling kit, approx $125 (I went through David at Northridge4x4, VERY impressed with the service) part number 1155200, which is a 1" boost rear, 2" boost front, and I think it's the best look and function for the least money if you want a slight boost and ability to fit 33 or 32 inch tires on a JK through year 2010.

OoPEZoO

I'm running a set of Rubi takeoff 32" KM's with 3.21's and a 6-speed. It drives just fine as long as you forget that 6th gear ever existed. I drive it like a traditional 5-speed, and it works out just fine. I'm running between 2200-2400 RPM at highway speeds of 62-68 MPH.

Its good enough for me until I can afford a regear and larger tires

Olean NY Jeeper

Just saw this thread, usually dont hang out in stock section ever. I have 34 inch Goodyear MTRs with Kevlar which measure about 34.2 inchs in diameter so they are as big as some of the smaller advertised 35s out there. I also have 3.21s with 6 speed. It isnt that bad on the road, u have to run in 4th and 5th gear a lot on the highway and when u r not on highway u spend all ur time in 4th or lower gear. 6th gear is no longer usealbe. Off road, it can be a challenge to go slow enough over rocks when rock crawling, but not impossible. It is livable while u save for gears. I plan on regrear but by the time I have enough cash it will be almost a year with stock gears. I would stay away from 33s and would just get the 35s. u will not be happy with 33s. The only people who defend 33s r people who bought them and r stuck with them. I have never heard ANYONE say, i hate my 35s, i want 33s. The opposite is quite common though.

08RedRecon

See attached to help you decide.

Mark Doiron

I'm running 33" DC FC IIs, 6-speed and 4.10 rear. I would not want to have a larger tire size or taller gears. It is marginally acceptable--but I'm one of those who doesn't recommend 35s without regearing (to 4.88s in my case). When I changed tires (from stock SRAs, along with other mod's, but, this was the one that heavily effected MPG's) I went from 20.5 MPG on a number of long trips to about 16.0 MPG on a number of long trips (67K miles total on my Jeep). That's a pretty big hit, especially when you consider that my favorite off-roading is long trips where distance between gas stops is huge--gas mileage is critical, and it has me pausing over whether I'll ever move up to 35s.