ok the stock tires on my mustang were 245/45/17's at all 4 corners and my stock gears were 3.27's


i have upgraded my front tires to 275/40/17's on 17x9" wheels, the rear tires to 315/35/17's on 17x10.5" wheels and at the end of the month will be putting in 3.73 rear gears.

I bought the speed calibrator thing, and have already set the multiplier to

1001001000 as the calculator on the Dallas Mustang Website says to put it at.

located at http://www.dallasmustang.com/page/pr...=&product=9910

now my question is

since the front tires are 275/40/17's and the rears are 315/35/17, will the front tires throw the speedometer off, or since they aren't driven by the drive axle, it just won't make a difference?

 

Fronts don't matter. Speed is calculated at the trans output shaft so rear gear and rear tire size is all that matters. And, if you tire only measures 26" (same as stock, which is around 26"), you only need to adjust for rear gear.

 

thats what I was thinking, but I just wanted to be absolutely sure. it sounded logical, but sometimes logic isn't always correct.

thanks