Need help from 96-99 GTS owners

[Go Fast For Life]

Can any one measure the tire heigth (or the diameter) of the stock 17" wheels and tires. I have 19" and want to know how much the speedo is off.

 

[C O D Y]

Try this site......

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

 

[opnwide]

I've got 19s and mine is off about 8%, according to a Dynojet, that plots rpm vs speed.

Your vipertech can retune your speedo.

 

[Finally got it !]

I have 19 also and through law enforcments speedo signs it looks to be 4mph off.. eg Shows 75mph on my gauge and sign shows 79mph

 

[FE 065]

Your RPM isn't off, use this formula to find true MPH

1. multiply your RPM times the TIRE DIAMETER


2. Next multiply your gear ratio (3.07) times 336


Divide answer 1. by answer 2. to get MPH@ your RPM for 4th gear


To find tire diameter, chalk a short line at the bottom of your tire and on the garage floor next to that line on the tire. Roll the car foward or backward until that line on the tire again is near the floor.


Mark another line on the floor, measure the distance between those lines and divide that distance by 3.14159.

 

[Big Medicine]

I have an excel spreadsheet set up to comp any combo. e-mail me if you want it & I'll reply with attached.

 

[VinR1]

...dont forget, you're also adding extra miles to your odometer