275/40/17 to 285/35/18 ?'S

[03DSG]

Does the diameter difference affect the rear end gearing in any way?

 

[Top_Fuel]

Diameter doesn't matter...it's the height of the tire that affects your gearing and throws off your speedometer.

Go to tirerack.com and look up the specifications of those two sizes. Specifically, look at height and/or revolutions per mile. The closer those two measurements are, the less your gearing will be affected. I believe there's less than 1/4" difference in height between those two sizes, so you're talking less than a 1% difference between 285-35-18s and the stock 275s.

-Greg

 

[FKing1]

Originally posted by Top_Fuel
Diameter doesn't matter...it's the height of the tire that affects your gearing and throws off your speedometer.

You are right on. The overall circumference is related to the overall tire diameter. A smaller circumference will act like a higher numerical gear ratio, like going from a 3:43 to a 3:73 for ex. Thats's why some of us put smaller tire/wheels on when going to the strip, it is like changing the rear end ratio.
Fred K.

 

[03DSG]

thanks!!