guys do u know of any program out there to correct for wheel size i see sc has but its only for truck applications.......any ideas....anyone.....

 

try this site - see if it helps http://www.miata.net/garage/tirecalc.html

 

thank man but it did not help what i need is something to actually change the size on the computer...........Superchip has something like that but only makes it for trucks.

 

nothing yet for the SXT's. i can think of only two ways to correct this.

1) match 20" tires to the same size diameter as your origianl 17's
2) contact dave at B&G Chrysler to see if he can reflash your PCM with the new tire diameter.



a 255/40-20 would keep your speedo accurate as they have the same diameter as your 215/65-17

 

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

Any reasonable size change won't change speedo enough to matter!