Looking to get 35's and I have seen a lot of people on here talking about how you need to change the gears for this. I haven't a clue. Is it true you will need to... how much will it affect performance without redoing gears.

 

Without regearing, your Jeep will feel like it has lost a lot of power and your overdrive or 6-gear will essentially be useless on long hill climbs. To regain stock performance, you will want 4.88 gears installed but if you want a little more power, I would highly recommend 5.13's. I did this and loved it.

 

Here are some other threads.

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

https://www.jk-forum.com/forums/show...ighlight=gears

https://www.jk-forum.com/forums/show...ighlight=gears

https://www.jk-forum.com/forums/show...ighlight=gears

https://www.jk-forum.com/forums/show...ighlight=gears

These are just a few threads if you search gears you will find more.

 

so the next question would be how much did it cost to have someone install it for you? Thanks for the help!

 

If you don't do the install yourself then the install will be whatever the rate is in your area for that type of work.

 

You're probably looking at somewhere between $1500-$2000. As Robar said, it all depends on what the going rate is where you are at.

 

If you are doing any highway driving I would highly recommend going with 488's. I had them in a Rubcon 5 spd and found that my rpms were pretty high with 35's and 488's. 513's also hae a weaker pinion.

 

What ratio do you have now? If you have the 4.10's, you may find that it's acceptable, at least for a little while. If you have 3.21's it'll be a dog.

 

If stock tires were 32's, going to 35's means your rpms drop about 9% from what ever they used to be in a given gear.

So, if you were cruising on your 32's at 3,000 rpm at a given speed/gear, with the 35's you'll be cruising at more like 2,745 RPM, a drop of ~ 255 rpm or so.

If that's enough to make you sad, then you'd want a gear swap.

Me, I've traditionally let the gearing go, it doesn't bother me enough to spend the time/$ on changing it. I might do a lower t-case gear set, as on the rocks I like the gearing back.

On a highway...what's the difference between the engine turning faster because I am a gear low but on larger tires, and a gear high and on smaller tires?

6 of one, a half dozen of the other.

"People talk about losing 6th gear" or whatever, but, the larger tires just made the shift pattern obsolete.....all the gears are merely turning at lower rpms.

This is an important point....pay attention newbies:

ME: "Damn, gas is so expensive, I'd better get some big ass tires on that jeep to bring my RPMs down and save some gas!"

Significant Other Required Typically To Authorize Major Expenditures: "Really, that works?"

ME: "Oh, Yeah, its like installing a deeper overdrive....remember when we used to have a 3 speed, and then overdirives came out to save gas?"

SORTTAME: "Oh, OK."

ME:

 

Agreed. Go for the power of the 5.13s ... I did and I like it!

You will rev higher but the 3.8 engine's power band is more responsive in the 3000 range . The stock gearing runs the engine in the 2000 rpm range for each gear. My 6th gear actually has some pull now and it was practically worthless before when I had stock tires and 3.21s. So why would you want stock performance out of 4.88s and 35s? You could spend more money on other power adders and you wouldn't see the difference that the 5.13s would give you. Plus the 5.13s don't cost any more extra $$ than having 4.88s installed.