Alltag

Tire Size Calculator

Compare two different tire sizes to see how they affect your speedometer and vehicle clearance.

Original Tire (OEM)

Format: 225 / 45 R 18

New Tire

Diameter Difference
—
—
Dimension Original New Diff
Diameter — — —
Width — — —
Sidewall — — —
Circumference — — —
Revs / Mile — — —
Speedometer Error
If your speedometer reads 60 mph, you are actually traveling at — mph.
Verwendung
  1. Enter your Original Tire size (Width / Aspect Ratio / Wheel Diameter) usually found on your driver's door jamb.
  2. Enter the New Tire size you want to upgrade or switch to.
  3. The calculator compares the two and determines exactly how much your speedometer reading and ride height will change.
  4. Note: Changing overall tire diameter by more than 3% is not recommended as it can affect ABS brakes and transmission shifting.

Formel

Tire Math:
Sidewall Height = Width (mm) × (Aspect Ratio / 100)
Overall Diameter = (Sidewall Height × 2) + Wheel Diameter
Circumference = Overall Diameter × π
Speedometer Error = (New Diameter / Original Diameter) × Indicated Speed

The Tire Size Calculator allows car enthusiasts to visualize the dimensional differences between tire sizes. Whether you are plus-sizing wheels or switching to winter tires, it accurately computes side-wall height, overall diameter, and speedometer inaccuracy.