Finally got my BBS LM reps installed on my car. They look sweeeeeeet.(pics will follow once i get her washed).

It is my understanding that now that i am on 18" rims, my speedometer will read approx. 7 mph faster than my previous 16's. With that being said, is it possible to recalibrate the speedometer so that it reads correctly with the 18s?

I know it's probably easier to just go with it as it is and keep in mind the 7mph difference, but i'd like to get your thoughts.

Thanks!

 

Vag that biatch up! (I hear that you can use a vag-com to alter wheel size or something like that!)

 

Wait...so you are saying that I am even slower than I think I am? That's just great [>:]

 

Sorry - i meant to say that the speedometer will indicate 7 mph slower than your actual speed when moving from 16" to 18" rims.

Ex:

w/16" @ 55mph indicated speed= actual 55mph
w/18" @ 55mph indicated speed = actual 62mph

Am i even correct in my assumption?

 

Oh...I like that description much better. Any body know if it is true??

 

I don't know how many times this has to be said but wheel size has nothing to do with the equasion. Its all about the circumference distance around the tire that matters. Anyone remember grade school?
Pi x Dia? = Circumference.

 

Thank you for the math lesson - but not all tires are the same size. Maybe i should have been a bit more specific by stating that i was running225/40/18over my old 205/55/16.

Upon doing further investigating, i found that the comparison between my old rims/tires and my new set yield a 0.8% reading that is too slow, therefore. When my speedometer reads 60, i am actually doing 60.5 mph.

http://www.miata.net/garage/tirecalc.html

 

You may want to look at the web site for the brand that your tires are also. Cause not all tires are created equal. They might be a different measurement than whats programed into that calculator. But the calculator is great for quick reference. Thanks for posting it.