Tire size calculator

Current tire size


/ R

New tire size


/ R

165/70 R14 vs 165/65 R15 comparison results:

Old New Diff %
Overall Diameter 23.09" 23.44" +0.35" (+8.90 mm) +1.52% Bigger sign. Arrow up
Width 6.50" (165.00 mm) 6.50" (165.00 mm) 0.00" (0.00 mm) 0.00%
Sidewall Height 4.55" (115.50 mm) 4.22" (107.25 mm) -0.33" (-8.25 mm) -7.14% Smaller sign. Arrow down
Rim Diameter 14" 15" +1" +7.14% Bigger sign. Arrow up
Ground Clearance +0.18" (+4.45 mm) Bigger sign. Arrow up
Circumference 72.55" (184.29 cm) 73.65" (187.08 cm) +1.10" (+2.80 cm) +1.52% Bigger sign. Arrow up

Speedometer difference

Original Speed (mph) New Speed with New Tires (mph)
20.020.3
30.030.5
40.040.6
50.050.8
60.060.9
70.071.1
80.081.2
90.091.4
100.0101.5

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.