Gear Ratio

Ive done some searching for this, but i cant find an excat answer...ive got a 97 4dr 4.0 5spd, and i am about to put a set of 32 11.50's on it, i was wondering on what ratio i should run for it to be back at stock...some people have told me to go with 4.10's or 4.56's but i know with either of them and a 5spd ill b standing my jeep up on 2 wheels (seen it done) so which should i go with

3.55
3.73
4.10
4.56

I'd say 4.56 for 32's and they would be good if you ever deside to go to 33's

I agree. Im buying a set of 4.56s and intend on running 32s. 4.56s will give you the best combination of power and economy.

4.56s....why regear again down the road?

This belongs in Mod Tech, but how many times can it be said?

32" tires?
4.56!!!

Yucca-Man said:

4.56!!!

Click to expand...

werd

4.88's if you see 35's in the near future and dont have a 8.25"

However, the man didn't ask what ratio y'all felt is best, he asked what ratio will get him back to stock -- which with a 5-speed means 3.07 gears.

I can tell you that 31" tires and 3.73 gears are exactly the same overall drive ratio as stock tires and 3.55 gears. As a rough generalization, a jump of one inch in tire size is roughly equal to jumping one change in gear ratio, so I'd guess that 32" tires and 3.73s would be close to the same as 3.07 gears and stock tires.

According to my tire/gear spreadsheet, 225/75 tires and 3.07 gears turns 2054 RPM at 55 MPH in 4th gear (which eliminates the differences in overdrive ratio for different years). With 32" tires, at 55 MPH in 4th gear 3.54 gears run at 2148 RPM and 3.73 gears run at 2263.

So my rule of thumb didn't work, and 3.54s would actually get you back to nearly the stock ratio, but I think 3.73s would be a lot more comfortable.

The problem is twofold. First off, the 3.07 stock gearing for a 5-spd is too high. They should have put 3.55 gears in the manuals to begin with. Second, because the larger tires are heavier and have greater rolling resistance, getting back exactly to stock ratios will still leave you with less than stock power.

So, for 32" tires (assuming you are absolutely certain you will NEVER go to larger tires! yeah, sure) I would suggest 3.73:1 gears as an absolute minimum. If you don't drive many highway miles, or live where there are a lot of hills, or want really good low gearing for off-road then I would suggest you look at 4.10:1 as a starting point. If you think larger tires are in your future then 4.56:1.