JS99Z

Please don't make fun of me to much for this question.

I recently changed my stock 16x8 wheels for 17x9 wheels with 275's on them. Do I need to program my computer and tell it that I have a different tire and rim. I don't know if this is true or not but, I heard the computer tells how much power to send to the wheels and when to shift (on an A4) according to how big of a rim and tire the car has to turn. Does that make any sense? If its true can it be done with a hypertech PPG?

Any input would be helpful.
Thanks

jd13

You're right and wrong in a way, but don't worry about that. Yes, you will need to reprogram your computer to tell it you have a different tire size on there. Yes, it can be done with the hypertech programer.

norcalstreet

Tire size doesn't have much of an effect on the shift points. The speedo will be off by only a few MPH. You only have to worry about this when you change your gears.

PhantomTA

The answer is NO..

the same computer calibration is used for cars that came with 275 40 17 and the guys with 16's

you dont need to do anything

Capn Pete

If you measured the outside diameter (OD) of your old 16's and the OD of your new 17's, given that the 17's are a lower profile, they should be about the same. If the 17's have a noticeably taller OD than the 16's, you could reprogram to input that change into the computer. Like Dave said though, cars with 245/50/16's and 275/40/17's came with the same programming.

jd13

Ok, so I was wrong. I learned something new also. I always thought you'd need to reprogram, but I guess not.