275/35R19 vs 285/30R20 Side-by-side tire size comparison with specs and compatibility
This tire swap is within the safe 3% diameter threshold. It should not cause issues with speedometer accuracy, ABS, or traction control systems.
Full Specifications Comparison
| Specification | 275/35R19 | 285/30R20 | Difference |
|---|---|---|---|
| Overall Diameter | 675.1 mm (26.6") | 679 mm (26.7") | +3.9 mm |
| Section Width | 275 mm (10.8") | 285 mm (11.2") | +10 mm |
| Sidewall Height | 96.3 mm | 85.5 mm | -10.8 mm |
| Circumference | 2120.9 mm | 2133.1 mm | +12.2 mm |
| Revolutions/Mile | 759 | 754 | -5 |
| Aspect Ratio | 35% | 30% | -5% |
| Rim Diameter | 19" | 20" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 275/35R19 to 285/30R20, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30.2 mph | +0.2 mph |
| 40 mph | 40.2 mph | +0.2 mph |
| 50 mph | 50.3 mph | +0.3 mph |
| 60 mph | 60.3 mph | +0.3 mph |
| 70 mph | 70.4 mph | +0.4 mph |
| 80 mph | 80.5 mph | +0.5 mph |
| 90 mph | 90.5 mph | +0.5 mph |
| 100 mph | 100.6 mph | +0.6 mph |
| 110 mph | 110.6 mph | +0.6 mph |
| 120 mph | 120.7 mph | +0.7 mph |
What This Swap Means
Wider tires (285/30R20): The 10mm 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.
Shorter sidewall: The 10.8mm decrease in sidewall height improves steering response and cornering precision. However, ride quality becomes firmer and the wheels are more vulnerable to pothole damage. This is a common trade-off when upsizing wheels (plus-sizing).
Ground clearance: Increases by 1.9mm, providing slightly better approach angles for off-road driving and speed bump clearance.