I am looking to re-gear for from 3.73 stock. Going to run 37-38's. I understand that higer gears means higher RPM's, but what is that RPM range at city speeds ( 35-45mph) and highway speeds (55-65+) ? Hows the gas mileage? THanks in advance!

 

Interested as well...subscribed!!!

 

Yes, just installed...and yes your RPM's will go up to get to the same speed, however if you buy a super chip you can change the timing on your gear changes and get back to normal. However you always will loose top speed.

 

I run 5.13's with 38" MT/R's.

There is a ratio/tiresize table available to help you. I'll find it and post it below.

I get pretty great gas mileage with my set up, but I run a superchip programmer as well as air intake and exhaust mods.

To sum it all up it can be handy to use this table. It is based on the above formula. You can use it to quickly estimate your trucks best gear ratio.

Tire Gear Ratio table (Tire size is on the left, gear ratio is up top, RPM's are in the table)

http://www.4x4offroads.com/gear-ratio-chart.html

Scroll down and the ranges are there. They also show preferred off-road (power), high-way (economy) and all-around RMP ranges.

Good luck!

 

Not haveing luck with search option. Appears to be broken right now. If you have some experience with the questions in the op and would like to share that would be appriciated.

 

Thank You, Sir! I like the calculator they give you to fingure things out. I like your setup using a superchip to time the gears and not get to reved up. Great info!

 

There is a JK specific gear chart in the FAQ of this forum.

Click the link and scroll down a bit.

https://www.jk-forum.com/forums/show...76&postcount=4

 

Ok, I've done the search & looked at the FAQ. Just as confused as before. I am running 4.10 now, and I'll be getting 33"s soon. I live in higher elevations, and tow a trailer so it looks like I should get 5.38s, but won't that higher rpm rate kill my mpg n wear on the engine, so should I just get 5.13s and call it good. BTW how much is a typical gear install cost.

 

I heard from local jeep shop to run motive gears ... What are opinions on that and what is good website to buy gears from ?

 

my installer boiled it down to this: for an automatic running 35s, 4.88 will return you to stock. 5.13 will give you "a little more oomph" and only increase your RPMs by @200 from 4.88s. Regearing should help with MPG because you need less gas pedal to reach the engine's powerband. "you only have to press the gas 1/4 to get to the usable RPMS, instead of all the way to the floorboards to make the transmission downshift" sounds logical to me so I am getting 5.13s installed in a week