Rotorhead

Jeep noob alert!

Ive got an 8.25 rear end (at least i think so after using the several identification pics floating around) and i have the factory tow hitch. Not sure if it was installed at factory cause i have the tow package or if it was added later.

Im lifted 4.5" running 31s and am wanting to go 32s or 33s. My question is what gearing do i currently have and am i bogging my engine too much by keeping the factory gearset?

danno74

if you have a 4.0 auto more than likely you have 3.55
im still running 3.55 on 33s but not for long, its doable but not ideal. hardly ever in overdrive.

biztyke

manual or auto? manual will have 3.07 gears, auto will have 3.55 or maybe 3.73 with a tow package. 31s are fine with stock gearing(auto or manual), but 32s or 33s i would look at 4.10 gearing, or even 4.56 if you go 33s.

Rotorhead

Auto tranny.

I just dont want to be shooting myself in the foot on gas mileage and available power by having stock gearing.

CMMC

The 4.0 will take quite a bit of "boggin" but I think this is the most acurate information out there. That is, unless your rear axle still has the tag attached to it that lists the gear ratio.

Rotorhead

How accurate are those gearing charts that compare tire size to tire size to find optimal gear ratio?

Rock Toy

Most aren't that accurate, mostly because, the one most people use is for a 1 to 1 transmission ratio, as in 4th gear in a manual and 3rd gear in an auto. To get the correct rpms you need to multiply the rpm shown for a gear ratio and tire height by either .75 for the auto or .79 for the manual.

mr white

I'm running 33s on 3.07s and its just fine. I don't drive it on the daily though and I drive pretty slow. lol

cdawall

Depends on the tire as well. 33x12.50R15 Bias ply Swampers feel like a dog, 285/75R16 Radial Cooper Disco S/T's feel fine plenty of power. They measure within half an inch of each other but good god those swampers are heavy. I still run stock 3.55s in mine I still get 18+ on the freeway. I am regearing to 4.88s to go to 35s after taxes with an 8.8 rear hopefully that will keep me in a nice power band with 35s on he freeway along with getting ok MPG's.

mr white

I've got boggers. Yeah, it's slow. Doesn't bother me though. :P

Metmknice

I will be going with 4.10s due to the great deals I have found recent. And I have /am staying with 31s.
4.10 is definitely minimum for 32-33, 4.56 will give you decent in-town mpg.

07Negative

If you plan on stickin w 31 or 32's. 4.10 gearing would be good. If you think or know you'll go to 33's or 35's. I'd say go with 4.56 gearing. Gives you wiggle room for larger tires.
But that's no joke tires definitely seem to make a little difference as to how these ratios work out in MPG and power.

Rotorhead

I think the largest I can see myself going is 33's.

Jared W

Im running 33x12.50x17 nitto mud grapplers and they are 10 ply. I currently have stock gears and am in need of gearing. Its fine, but after driving it all day (because it is my DD) it kinda dogs it out. If you go 33's a 4.56 is right on the money, thats what im going for because I have 33s and once you get there youll be thinkin about them 35s