Ive just fitted 17" VT SS mags to my SL 5 speed. Problem is my speedo is still calibrated for the stocko 14 inch wheels. If I do 100 Km/h by the speedo, what speed am I actually going. Some original photos have not been recovered yet.

Hey man, I just go VXSS wheels put on about 3 weeks ago. I worked my spedo to be out by 0.5km/h when going at 100km/h. It depends on the tyres you have. I have 235 it changes if you get 225, etc.

Yeah, Ive got 235's on mine as well.

mate you can have 365 it aint goin to change your speedo....however 225/45 17 and 225/60 17 thats when the speedo will come in to play.........60 being taller then 45 but yeah going from 14" to 17" will change the speedo as well......but you can get them calibrated....someone on here will know where...

calculate the distance of one roatation of a 14" wheel, and then of your new 17" wheel, find the percentage difference and then calculate the error of your speedo. Piece of piss....

Does anyone know any places in Melbourne , preferably in the South Eastern suburbs, where I can get my speedo calibrated.

jack the back of ur car up and draw a line on ur tailshaft and a line on ur tyre rotate the tyre until the tailshaft is in the original spot then u can calculate the error because of the space that wheel hasnt turned, or simply take it to a workshop and get them to change the size of ur speedo gear

http://www.miata.net/garage/tirecalc.html just go check the tyre card on the inside or ure glove compartment. the two 14's are the same at 100k's, but the 15" they got there is 2.5km faster or slower than the 14's, cant remember. i'm to lazy to check. all i know is that my 195x60x15 r too slow at 100 im really doing 96.8. chris.