Speedometer Off?!

[Goonz SVT]

Is your speedometer usually off when you upgrade to bigger wheels? Ever since Ive been driving with my 18s, I felt as if my speed on the speedometer wasnt right to what it felt while driving. Is that a factor or the tire size? I have 215-40-18

 

[KerryKool]

Yea, if you upgrade to bigger tires (in your case) your speedo is behind normal speed, if you upgrade to smaller tires, your speedo is ahead of normal.

The miata tire calc works awesome calculating what the difference is between current and stock tire sizes.

Here:http://www.miata.net/garage/tirecalc.html (need java script)

 

[CSVT1214]

You should not notice any difference at all. Even though it's off, it's so minor you can't "feel" it or even see it.

Traveling 60 mph = 59.7 mph on the speedometer.

 

[todras]

With 17"'s I GPS'd my Tour. It reads 3mph under what it should be at 75 mph. Helps me keep out of tickets. I'll have to see what it reads with the stockers on this winter.

 

[Steeda...]

Mine was 3mph slow with the stockers as well accoarding to todds GPS