Tire size calculator

215/60 R18 vs 235/55 R18 comparison results:

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	Old	New	Diff	%
Overall Diameter	28.16"	28.18"	+0.02" (+0.50 mm)	+0.07%
Width	8.46" (215.00 mm)	9.25" (235.00 mm)	+0.79" (+20.00 mm)	+9.34%
Sidewall Height	5.08" (129.00 mm)	5.09" (129.25 mm)	+0.01" (+0.25 mm)	+0.19%
Rim Diameter	18"	18"	0"	0.00%
Ground Clearance			+0.01" (+0.25 mm)
Circumference	88.46" (224.69 cm)	88.52" (224.84 cm)	+0.06" (+0.16 cm)	+0.07%

Speedometer difference

Original Speed (mph)	New Speed with New Tires (mph)
20.0	20.0
30.0	30.0
40.0	40.0
50.0	50.0
60.0	60.0
70.0	70.0
80.0	80.1
90.0	90.1
100.0	100.1

Welcome to our handy wheel and tire size calculator!

Put your current tire size(width, aspect ratio, and diameter) into the first form, then your desired size into the second form and you will get the difference between the new and tire size. Also, determine the speedometer reading difference and the actual speed with a new set of tires. You can use both metric and flotation sizes for your vehicle.

Our tire calculator could help decide whether tires and wheels will fit into your car. If you need to compare tires by brand and model use our tire comparison tool.