JeepDog

Ok gang I checked and searched and I came close but no cigar.

From what i understand you can't program the PCM for larger tires. (Outside the available ratios from the factory)

So what gear AND tire size will give the same Speedometer reading as the stock Rubicon with 32's and an auto?

In others words what new Wheel and gear combo is equivalent to the stock stuff?

I.e. 37inch tires and 5.13's give the same rpm as 32' and 4.10 (NOTE!!! This is an EXAMPLE only I do NOT know if this is true. HENCE the question. Thanks!)

Just curious.

SabrToothSqrl

what we have here kids is a 6th grade math problem... luckily for me my 6th grade sister is near by!

Original tires = 32" gears = 4.11


32/4.11 = 7.79 (ABOUT)

Now you want to know what gears will fit a size..

SO

say 35s...

35/X = 7.79 (or, divide each side by 7.79 for the mathless)

35 / 7.79 = 4.4929396662387676508344030808729

4.56s would get you really close...

same goes for the 37s...

37 / 7.79 = 4.7496790757381258023106546854942

or 4.88s

the 7.79 is the ratio you need.

1 "gear" = 7.79 inches of tire...

Now keep in mind this is only math; and a 37 weighs a lot more than a 32... so snappy highway feeling may mean going lower (math higher) in gear ratio

Man, math finally paid off for me!

usmcdoc14

BUT
aluminum is heavier than rubber and air so if you go from a 32 on a 17"rim to a35 on a 16" rim (or even 15") your rotational mass may be less.

just wanted to toss that wrench in the confusion

JeepDog

Thank you. NOW we have a result for people searching to do this.