Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 9 of 9 Posts

·
Registered
Joined
·
92 Posts
Discussion Starter · #1 ·
Does anybody know anything about these cause I've been readin up on them and they sound awesome. I just put 35" 12.50 tires on my jeep and its really struggling up steep road inclines, will this help at all???
 

·
Registered
Joined
·
163 Posts
Jason366433 said:
Does anybody know anything about these cause I've been readin up on them and they sound awesome. I just put 35" 12.50 tires on my jeep and its really struggling up steep road inclines, will this help at all???
Sounds like you need to look into a regear.
 

·
Registered
Joined
·
163 Posts
Jason366433 said:
What do you mean by regear. What do you suggest.
Now that you put 35's on your Jeep, you need to consider changing the gear ratio in your differentials. The larger tire is harder to spin. What motor/transmission do you have?
Also, do a search for regear. You'll find tons of information.
 

·
Registered
Joined
·
92 Posts
Discussion Starter · #6 ·
cixpak88 said:
Now that you put 35's on your Jeep, you need to consider changing the gear ratio in your differentials. The larger tire is harder to spin. What motor/transmission do you have?
Also, do a search for regear. You'll find tons of information.
I believe it's just the standard transmission that comes with a factory jeep
 

·
Full Size Jeep Dr.
Joined
·
3,432 Posts
With 35" tires and a standard transmission, 4.88 is the absolute minimum for a gear ratio. If you've got a 4 cylinder engine, then drop down to 33s as soon as you can!
 

·
Knows a couple things...
Joined
·
49,624 Posts
The correct "fix" to restore the power lost after having installed big tires like 35" is to regear the axles. Big tires reduce the engine RPMs at any given speed and with lower engine RPMs, the less power the engine puts out... and with 35" tires, the engine isn't putting out enough power to make driving with them any fun since its RPMs are lower than they should be.

Replacing the ring & pinion gears (they come as a set) inside both axles restores the engine rpms that were there when the factory shipped the Jeep... that is the ONLY way to correctly restore the power lost from having installed big tires. The ring & pinion gears are what connect the axle shafts to the driveshafts... and a 4.88 ratio, for example, means the driveshaft will turn 4.88 times for every single axle shaft rotation. The lower the ratio, and 4.88 is a lower ratio than the 3.07 or 3.73 the factory typically installs, the higher the engine rpms. And raising the RPMs back up to where they should be does not mean they become excessive on the highway... properly regearing the axles simply means the engine rpms are back to where they should be.

Think of it this way... the big tires have made your 1st gear RPMs more like they were before when you were in 2nd gear... so it's harder to start off from a stop. And in 5th gear, your RPMs are too low on the highway so you have to spend more time in 4th gear.

Regearing your axles to the right ring & pinion ratio will correct all of that. And the correct/most optimal axle ratio for 35" tires with the 4.0L engine and 5-speed manual transmission is 4.88. Other engines and transmission combinations will usually require a different ratio. What engine & transmission do you have?

The cost to regear both axles with all parts & labor is $1100-1300 or so.

Installing a chip will NOT be the right fix...such chips only do anything at or near redline RPMs and wide-open throttle. Regearing your axles (both must be regeared) will restore properly the power at all speeds & engine RPMs.
 

·
Registered
Joined
·
111 Posts
It will give you a little more "pep", but will not compesate for the 35s. As stated above, you need to regear. I noticed better throttle response, it got rid of the "dead spot" right off idle, and I haven't thrown a P0431 code since I installed my Flash Paq. Keep in mind, alot of the "advanced features", such as speedo correction, are only avaliable for the Rubicon.
 
1 - 9 of 9 Posts
Top