Formula & Calculation Methodology
Overall Diameter (mm) = Rim (inches) * 25.4 + 2 * ((Width * Profile) / 100).
Step-by-Step Worked Example
Stock: 185/65 R15 (621.5 mm) -> New: 195/60 R16 (640.4 mm)
- Diameter Change: +18.9 mm (+3.04%)
- Permissible Safety Range: +/- 2.5%
Result: High Risk (3.04% Error): Exceeds safe 2.5% threshold. Consider 195/55 R16 instead.
Frequently Asked Questions
What is the maximum safe tyre upsize limit?
Automotive experts recommend keeping overall diameter variation strictly within +/- 2.0% to 2.5% to maintain ABS calibration.
Related Tools & Calculators