braverichard

I'm considering purchasing a set of new 16 inch chrome wheels mounted on P225/R60 tires for my 84 300SD. I was just wondering, since the car's original equipment was P195/70R14 tires, will the change in aspect ratio affect the accuracy of my speedometer? Any assistance would be greatly appreciated.

Thanks all.

Mercedes Tuner

http://www.1010tires.com/tiresizecalculator.asp



TIRE #1 - 195/70R14 / TIRE #2 - 225/60R16
Section Width: 7.67 in 195 mm / Section Width: 8.85 in 225 mm

Rim Diameter: 14 in 355.6 mm / RimDiameter: 16 in 406.4 mm

Rim Width Range: 5.5 - 7 in / Rim Width Range: 6 - 9 in

Overall Diameter: 24.74 in 628.39 mm / Overall Diameter: 26.62 in 676.14 mm

Sidewall Height: 5.37 in 136.39 mm / Sidewall Height: 5.31 in 134.87 mm

Radius: 12.37 in 314.19 mm / Radius: 13.31 in 338.07 mm

Circumference: 77.72 in 1974.0 mm / Circumference: 83.62 in 2123.9 mm

Revs per Mile: 840.7 / Revs per Mile: 781.3

Speedometer1: 60 mph 100 km/h / Speedometer2: 55.7 mph 92.9 km/h

Speedometer Difference: 7.602% too slow Diameter Difference: 7.07%

braverichard

Thanks a million for giving me the link to that site. All my questions have been answered now.

Mercedes Tuner

No Problem!

aznmode

I'm a little confused. Is this saying the bigger the tire the slower you are really going? I thought it was the opposite. Maybe I'm reading it wrong.

amdeutsch

The bigger the overall diameter the faster you are going with the speedometer actually showing a slower speed.

aznmode

Got it. So based on that site, it looks like instead of going 60mph I'm actually going 59.2mph on my new shoes. Not bad. I thought it was at least 3mph difference.