You are correct.
Originally Posted by precisionxt
It's a 2.5% difference with 185-55-15 tires. So when your odometer says 97500 miles, your car has really gone approximately 100,000 miles. So you get an extra 2500 bonus miles of powertrain warranty coverage.
I just replaced my tires and went with 185-60-15 this time for the additional height. These tires cause the speedometer to be low by roughly 5.5% (4mph at freeway speeds). When my speedometer (and Scangauge) say 60mph, my GPS says I'm going 64mph. That was my goal because I do a fair amount of freeway driving and I generally keep my RPMs at/below 3000.
Completely unrelated...but I wonder if anyone has ever checked a 100% stock Mirage with GPS to verify the accuracy of the speedometer calibration?
View my fuel log 2015 Mirage ES 1.2 manual: 52.1 mpg (US) ... 22.2 km/L ... 4.5 L/100 km ... 62.6 mpg (Imp)