🚗 Automotive
Calculator
Tire Size Calculator
Never guess if your new tires fit. Calculate exact dimensions.
How to Use This Tool
- Enter tire section width in mm.
- Enter aspect ratio percentage.
- Enter rim diameter in inches.
- Get overall diameter and circumference.
The Formula
Diameter = 2 × (Width × Aspect Ratio / 100) + (Rim × 25.4mm).
Why It Matters
Your car came with 225/45R18 tires (25.5-inch diameter). Considering 235/40R19 (25.8 inches) — a 1.2% increase. Your speedometer will read slightly slow. This small change also affects your ABS calibration.
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