235/50R19 vs 245/45R20 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 | 235/50R19 | 245/45R20 | Difference |
|---|---|---|---|
| Overall Diameter | 717.6 mm (28.3") | 728.5 mm (28.7") | +10.9 mm |
| Section Width | 235 mm (9.3") | 245 mm (9.6") | +10 mm |
| Sidewall Height | 117.5 mm | 110.3 mm | -7.2 mm |
| Circumference | 2254.4 mm | 2288.7 mm | +34.3 mm |
| Revolutions/Mile | 714 | 703 | -11 |
| Aspect Ratio | 50% | 45% | -5% |
| Rim Diameter | 19" | 20" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 235/50R19 to 245/45R20, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 mph |
| 40 mph | 40.6 mph | +0.6 mph |
| 50 mph | 50.8 mph | +0.8 mph |
| 60 mph | 60.9 mph | +0.9 mph |
| 70 mph | 71.1 mph | +1.1 mph |
| 80 mph | 81.2 mph | +1.2 mph |
| 90 mph | 91.4 mph | +1.4 mph |
| 100 mph | 101.5 mph | +1.5 mph |
| 110 mph | 111.7 mph | +1.7 mph |
| 120 mph | 121.8 mph | +1.8 mph |
What This Swap Means
Wider tires (245/45R20): 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 7.2mm 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 5.4mm, providing slightly better approach angles for off-road driving and speed bump clearance.