Does anyone know if I can get a higher rear end gear (lower number) for my 2007 than 3.42? I would like a 3.08 if possible. I checked with the vendors awhile back and nothing was available.

 

nothing higher than 3.42 available

 

I don't think you would want anything taller than a 3.42, especially with your "newer" G56 gearing. I have the same gears/transmission in my '08 and, at 63mph, I am at 1600rpm. 1600rpm is about the lowest you can go at cruising speed and still get good mileage (i am assuming you want the tallest gears you can in order to maximize highway fuel economy). Any lower than 1600rpm and the MPG drops.

 

Adding 285/75/17 with 3.42's will get you close, 3.17.

MikeyB

 

MikeyB -
How do you calculate that? I'd like to know what mine is with my 3.73 and 325/60/20's.

Thanks in advance
B

 

I created an excel spreadsheet with the formulas.

The 325/60/20 is roughly 35.3" tall (depending on the manufacturer) so your new ratio is 3.31

MikeyB

 

Try this, http://www.1010tires.com/TireSizeCal...bmit&reset=yes

Then enter the diameter data in this, http://4lo.com/calc/geartire.htm

Quick search couldn't find one that does it all.

 

My desire is to get the best MPG. I could go with taller tires but the problem is they are also fatter and more rubber on the road and more sidewall to flex which reduces MPG. So I'd like to stay with the original tire and reduce RPM with gearing. I've looked into the overdrive units but doubt I'd recoup the cost of $3000.

 

On a 4x4 it takes quite a while to recoup all the money for 2 gear swaps. On a 2wd, obviously it would take 1/2 the time. I would love to drop back from my 4.10s to a 3.42, but I just cant take the jump. It would take a very long time for the money to add up for a 1-2 even maybe a 3mpg gain. In town I would expect my mileage to actually drop with the 3.42s as it take more power to move those gears vs the 4.10s...

Its a slippery slope for most of us.