Try our official app! Developed by Calculatoric Team:
Tire Size Calculator
Enter metric sizing (width / aspect ratio / rim). Results update as you type.
Tire size
New rim diameter only
See diameter difference and whether Tire 2 reads faster or slower on your speedometer vs Tire 1 (stock).
Stock / current tire
New / alternate tire
When your tires are taller or shorter than factory, the speedometer lies. Enter indicated speed to see actual road speed.
Factory tire
Tire you installed
Lists common sizes within ±3% of your target diameter—useful when changing rim diameter but keeping similar rolling height.
Your target tire
How to read a tire size: In 265/70R17, 265 is tread width in millimeters,
70 is the sidewall height as a percent of width (aspect ratio),
R means radial construction, and 17 is wheel rim diameter in inches.
Overall outside diameter ≈ rim + (2 × sidewall). Sidewall height = width × aspect ratio ÷ 100.
Label
Meaning
Example 265/70R17
Width
Tread width (mm)
265 mm
Aspect
Sidewall % of width
70% → 185.5 mm sidewall
Rim
Wheel diameter (in)
17 in
Overall Ø
Total tire height
≈ 31.6 in
Revs/mi
Rotations per mile
≈ 638
Special
A tire’s sidewall code—like 265/70R17—hides more than width and rim size. This tool turns those numbers into overall diameter, rolling circumference, and revolutions per mile so you can compare upgrades, check speedometer drift, or find plus-size options that stay close to stock.
