255/55R19 vs 275/55R20 Side-by-side tire size comparison with specs and compatibility
This tire swap exceeds 5% diameter difference. Not recommended without suspension modifications. Will significantly affect speedometer, ABS, and may cause rubbing.
Full Specifications Comparison
| Specification | 255/55R19 | 275/55R20 | Difference |
|---|---|---|---|
| Overall Diameter | 763.1 mm (30") | 810.5 mm (31.9") | +47.4 mm |
| Section Width | 255 mm (10") | 275 mm (10.8") | +20 mm |
| Sidewall Height | 140.3 mm | 151.3 mm | +11 mm |
| Circumference | 2397.3 mm | 2546.3 mm | +149 mm |
| Revolutions/Mile | 671 | 632 | -39 |
| Aspect Ratio | 55% | 55% | 0% |
| Rim Diameter | 19" | 20" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 255/55R19 to 275/55R20, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 31.9 mph | +1.9 mph |
| 40 mph | 42.5 mph | +2.5 mph |
| 50 mph | 53.1 mph | +3.1 mph |
| 60 mph | 63.7 mph | +3.7 mph |
| 70 mph | 74.3 mph | +4.3 mph |
| 80 mph | 85 mph | +5 mph |
| 90 mph | 95.6 mph | +5.6 mph |
| 100 mph | 106.2 mph | +6.2 mph |
| 110 mph | 116.8 mph | +6.8 mph |
| 120 mph | 127.5 mph | +7.5 mph |
What This Swap Means
Wider tires (275/55R20): The 20mm wider contact patch provides better grip in dry conditions and improved cornering stability. However, wider tires increase rolling resistance slightly, which may affect fuel economy by 1-2%. They are also more susceptible to hydroplaning in wet conditions.
Taller sidewall: The 11.0mm increase in sidewall height provides a more comfortable ride by absorbing more road imperfections. Taller sidewalls also offer better protection against pothole damage to wheels. The trade-off is slightly less responsive steering feel.
Ground clearance: Increases by 23.7mm, providing slightly better approach angles for off-road driving and speed bump clearance.