Rim Width Calculator
Find the minimum, maximum, and optimal wheel width required to safely support your specific tire size.
Quick Answer
A standard 245mm wide tire safely fits on rims ranging from 7.0 inches to 8.5 inches wide. However, mounting this tire specifically on a 7.5-inch or 8.0-inch rim is considered the "ideal" fitment for maximizing tread life, steering response, and safety.
Rim width fitment chart (ETRTO standard)
| Tire Width | Recommended | Acceptable |
|---|
Minimum and Maximum Rim Widths by Tire Size
| Tire Width (mm) | Minimum Rim (in) | Ideal Rim (in) | Maximum Rim (in) |
|---|---|---|---|
| 215 mm | 6.0" | 7.0" | 7.5" |
| 235 mm | 6.5" | 8.0" | 8.5" |
| 255 mm | 7.0" | 8.5" | 9.0" |
| 275 mm | 7.5" | 9.0" | 9.5" |
| 295 mm | 8.0" | 10.0" | 10.5" |
| 315 mm | 8.5" | 10.5" | 11.0" |
Formula
Ideal Rim Width (in) = (Tire Width in mm ÷ 25.4) × 0.85
- Width converted to inches then multiplied by 85% keeps sidewalls perfectly vertical
- Minimum = 70% of section width in inches
- Maximum = 90% of section width in inches
- Example: For 275mm: (275 ÷ 25.4) × 0.85 = 9.20" → round to 9.0"