Tire Size Calculator & Comparison
A tire size like 225/45R17 means a 225 mm wide tread, a sidewall 45% as tall as that width, and a 17-inch wheel. Its overall diameter is about 25.0 inches. Enter one size to see its dimensions, or two to compare diameter, revolutions per mile and speedometer error. Staying within 3% is the usual rule.
Results are general information, not mechanic advice. Have a qualified mechanic or tire shop check fitment, speedometer calibration and gearing before you change parts.
FAQ
What does 225/45R17 mean?
225 is the tread width in millimeters, 45 means the sidewall is 45% as tall as the width, R means radial construction, and 17 is the wheel diameter in inches.
How much bigger can I go on tire size?
A common rule of thumb is to stay within 3% of the original overall diameter to limit speedometer error and clearance problems. Always check load index and speed rating too.
Does a bigger tire change my speedometer?
Yes. A taller tire covers more ground per turn, so you're going faster than the speedometer shows. The calculator shows your true speed at an indicated 60 mph.
How do I calculate tire diameter?
Diameter = wheel size + 2 脳 sidewall. Sidewall = width in mm 脳 aspect ratio 梅 100 梅 25.4 to convert to inches.