Just curious about this. also is there a way to correct it? my car came stock with the 18s but i assume the overall tire diameter is the same as the guys with the 17s, but i don't know.

any help on this would be great. i am not saying i am going to change, just curious if i ever did how it would change the spedo and odo.

 

Shouldn't be much of an issue, especially if you use OEM tire sizes (a 255 for the 17s vs a 245 for 18s). The slightly thicker tire should offset the slightly smaller rim. Are you looking for 17s? Any chance you might want to trade your 18s for my 17s?

 

with my wheels i get 13 mpg.... im on 19s.

 

Use this link to find out the difference between tire and rim sizes.

http://www.net-comber.com/tirecalc.html

 

I believe stock sizes are:

225/55R17
245/45R18

The 17" tire diameter is about 63 thousandths of an inch larger than the 18" tire (a negligible difference).

 

http://www.1010tires.com/tiresizecalculator.asp

put in your stock and what size you want to put and it will tell you exactly the amount it will mess with your spedo and odo.

 

Are your wheels made of solid gold?

I am on 19s as well and get between 17-21 mixed driving.