Jeep Wrangler Forum banner

1 - 7 of 7 Posts

·
Abe Froman
Joined
·
3,786 Posts
Discussion Starter #1
How bad is this setup? I have a 2000 with the 3 speed auto tranny and currently run 33x10.5x15 which I love. Can I just deal with it or will it be that bad? My Jeeping buddy just put on 37" tires and asked if I wanted his 35" tires and rims for free. I can't pass a deal like that up no matter what. If I run the 35's with my tranny and I want to regear what gearing should I go to?
 

·
Registered
Joined
·
585 Posts
if you're getting them for free, then just try it and see how bad it is. i have the same transmission and one of these years when i get to 35's, i'll be going with 4.56 gears.
 

·
Registered
Joined
·
610 Posts
You'll be much happier with 4.88's with 35's and an auto. Consider 5.13's if you have D44's and if you don't get a HP30 and build that until you are ready for the 35's.
 

·
Registered
Joined
·
77 Posts
There is a mathematical formula for this. It calculates the number of inches your vehicle moves forward with each turn of the driveshaft. Then you can figure what gear ratio gets you the closest to that for what tire size you want to use. Just make the appropriate substitutions in the formula.

tire height in inches x 3.14 / gear ratio = roll out

The closer that you stay to the stock number the more stock the jeep will run, the more accurate the speedometer will be, etc.

Jeremy
ASE Master Auto Tech
 

·
Registered
Joined
·
585 Posts
i always look at it like it's a ratio of gearing to tire height and you want the new ratio to equal your factory ratio.

factory gearing: 3.73
factory tire height: 30
new tire height: 35
new gear ratio: unknown (x in the equation)

3.73/30=x/35
solving for x gives you a ratio of 4.35 which doesn't exist, so you can either stay with the 4.10s or go up to 4.56s.
 

·
Knows a couple things...
Joined
·
49,021 Posts
With the OP's 3-speed 32RH transmission, 4.56 is ideal for 35" tires. 4.10 would work, an automatic transmission is more forgiving of an improper axle ratio, but the engine RPMs would be a little lower than would be optimal.
 
1 - 7 of 7 Posts
Top