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sohl · 07-01-2008, 02:28 PM

Here is a comparison of the old and new tire sizes taken from http://www.miata.net/garage/tirecalc.html:

Code:

Specification Sidewall Radius  Diameter  Circumference  Revs/Mile  Difference
195/55-15     4.2in    11.7in    23.4in         73.7in        860        0.0%
195/60-15     4.6in    12.1in    24.2in         76.1in        833        3.3%

So at freeway speeds, a 3100 RPM before is now about 3000 RPM. That seems consistent with what I've observed. I'll still try to confirm the estimated 3.3% discrepency on my odometer using a GPS.

07-01-2008, 02:28 PM	#13 (permalink)
sohl Ecomodding Dabbler Join Date: Jun 2008 Location: Detroit Area Posts: 43 LilRed - '03 Mazda Protege LX 90 day: 29.09 mpg (US) Thanks: 0 Thanked 1 Time in 1 Post	Tire Size Comparison Here is a comparison of the old and new tire sizes taken from http://www.miata.net/garage/tirecalc.html: Code: Specification Sidewall Radius Diameter Circumference Revs/Mile Difference 195/55-15 4.2in 11.7in 23.4in 73.7in 860 0.0% 195/60-15 4.6in 12.1in 24.2in 76.1in 833 3.3% So at freeway speeds, a 3100 RPM before is now about 3000 RPM. That seems consistent with what I've observed. I'll still try to confirm the estimated 3.3% discrepency on my odometer using a GPS. __________________ Last edited by sohl; 07-01-2008 at 02:38 PM..