got my gears installed to today and with the hypertech i changed the setting for the 373 gears and it asks the next question tire height? i know my tire is a 17 inches, but its asking from 24" to 30" what would be my tire height? what should i put? i have P275 40zr17 tires..thanks

 

http://www.sstire.com/tireheights.html

Or you can go to tirerack.com and look up your specific tire. It will give you all the specs on it.

 

Technically a 275/40/17 is about ~25.66", but 25.5" should work. If you went with 26.0", then your speedo would read a little bit slow, and you could caught for speeding even when you think you're doing the speed limit. Better be safe than sorry.

 

easy. Draw a line with chalk on your tire and where it meets the ground. Then have a friend roll the car one full tire rotation until the line is straight. then measure the gap.

 

Its exactly 25.66 for your tire size.

 

what he said

 

on the hypertech 25.66 is not available, not listed, would 25.5 be good to use or 25.7? which would be more accurate for the speedo to read correctly?

 

I always round up! This way the speedo will be reading a little faster than you are actually going, not really enough to make a difference though.

Richard

 

actually rounding up will cause the speedo to read SLOWER,but its negligable.

If I remember correctly selecting 25.7 in the HPP3 with make your speedo read about .9 mph slower then the actual speed. using 25.5 will give your speedo about a 2.5 MPH too fast reading.

25.7 is the one to use