Good day,

Looking for some thoughts.

I am wanting to change the rear gear ratio on my IROC. Currently have a fourth gen rear installed.

Rear tires are 18x10.5 (285/35/18) and the wheel/tire is a little over 26 inches tall.

What would be an appropriate rear gear to use with this wheel/tire combo. Been debating on either 3.73 or a 4.10.

Car is NOT daily driven, I do care a bit about gas mileage as I do a lot of back road driving with the car but I also want to launch hard from a stop and be able to break the tires loose if I want to.

Engine is not stock and has a Mini-Ram installed.

Thoughts?

 

I'm running 275/40/18 in the rear of mine with a t5, 4th gen rear and 3.90 gears. Seems to be a happy medium. It launches very well and pulls like a freight train, but at cruising speed it doesn't rev to the moon.

The transmission that's in your car will make a difference in your choice as well...

 

It's an auto 700R4.

 

What are you cruising at and what are the RPMs? Peoples definitions of acceptable cruising RPMs differ. Heck, my definition changes based upon engine size and cylinder number.

 

3.42 axle ratio gives more than enough final drive ratio for a typical street performance engine with 700R4 trans. Think in terms of final drive ratio, not the axle ratio.