I checked the tire calculator and it said "Speedometer reading with non stock tire is 2.1% too fast. When your speedo said 60mph you are actually traveling 58.8mph.

My question is does this mean your car accumulates more or less miles than normal on the odometer?

 

You accumulate more, when you've done 100 miles your odometer records 102.1 miles.

 

yep, you accumulate milage a little faster, however, the other side effect is that your gearing is a little taller....giving you quicker acceleration...

 

Since it is off only 2.1% this is pretty much insignificant (at least to me) an issue.

Think about it...by 100,000 miles you will be 'off' only 2,100.

 

I'm running 245/45/18, mine is off by more than 3% too slow, but it doesn't really bother me

 

Isn't there a way to reset/adjust the speedo? No it's not that big of a deal but the next time you need service at a dealer they should be able to adjust it, if it bothers you that much.

 

You know, the other interesting thing is that these 'speedo errors' don't address at all the inherent margin for error of the (mass produced...often by the lowest bidder) speedo calibration itself, nor does it address the different speedo readings as time goes on due to simple tire wear. As they wear, tires are no longer the exact same diameter as when new, so right there you are talking about inherent error rates.

Bottom line to me is unless it is WAYYYYY off, who cares!!

 

Thanks for all the quick replys. I now feel a whole lot better on the situation. Your right! Who Cares!! I will be getting the Kuhmo Escta MX's thanks to Mr. JJS!!! Thanks for all the helpful information bro!

 

No way man!!!! I just gave you some pitfalls/concerns...you picked 'em!!!!

Enjoy!!

 

It was these or the 245/45's. I heard the 235's are better in width than the 245's for OEM 17's.
I think I'll be alright. Others are running the same setup.
Thanks again.