Calculate tire diameter, tire height, sidewall height, circumference, revolutions per mile, ride height change, and speedometer difference. Use this tire diameter calculator to compare current and new tire sizes.
Tire diameter:
Uses tire width, aspect ratio, and wheel diameter to calculate total tire height.
Compare diameter:
Compares current and new tire sizes to show diameter difference, sidewall difference, circumference difference, and ride height change.
Speedometer change:
Estimates actual speed after changing tire diameter.
Revolutions per mile:
Calculates how many times the tire rotates over one mile based on circumference.
A tire diameter calculator helps estimate how tall a tire is before changing tire sizes.
It can help compare fitment, speedometer change, ride height, wheel gap, gearing feel, odometer change, and tire revolutions per mile.
Your result shows tire diameter, sidewall height, circumference, revolutions per mile, diameter difference, percent difference, ride height change, and actual speed estimate. These are estimates based on the values you enter.
Multiply tire width by aspect ratio to get sidewall height, convert it to inches, double it, then add the wheel diameter.
Tire diameter is the overall height of the tire from the bottom to the top when measured through the center of the wheel.
Yes. A larger tire diameter usually makes actual speed higher than the speedometer reading. A smaller tire diameter usually makes actual speed lower.
Many tire changes aim to stay within about 3% of the original diameter, but fitment depends on the vehicle, wheel size, clearance, load rating, and manufacturer guidance.