225/50R18 vs 245/45R19 Side-by-side tire size comparison with specs and compatibility
This tire swap is between 3-5% diameter difference. Check for fender clearance and be aware of speedometer error. May require recalibration.
Full Specifications Comparison
| Specification | 225/50R18 | 245/45R19 | Difference |
|---|---|---|---|
| Overall Diameter | 682.2 mm (26.9") | 703.1 mm (27.7") | +20.9 mm |
| Section Width | 225 mm (8.9") | 245 mm (9.6") | +20 mm |
| Sidewall Height | 112.5 mm | 110.3 mm | -2.2 mm |
| Circumference | 2143.2 mm | 2208.9 mm | +65.7 mm |
| Revolutions/Mile | 751 | 729 | -22 |
| Aspect Ratio | 50% | 45% | -5% |
| Rim Diameter | 18" | 19" | +1" |
Key Impact Summary
Speedometer Correction Table
When switching from 225/50R18 to 245/45R19, your speedometer will under-read. Here is the correction at common speeds:
| Speedometer Shows | Actual Speed (mph) | Difference |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 mph |
| 40 mph | 41.2 mph | +1.2 mph |
| 50 mph | 51.5 mph | +1.5 mph |
| 60 mph | 61.8 mph | +1.8 mph |
| 70 mph | 72.1 mph | +2.1 mph |
| 80 mph | 82.5 mph | +2.5 mph |
| 90 mph | 92.8 mph | +2.8 mph |
| 100 mph | 103.1 mph | +3.1 mph |
| 110 mph | 113.4 mph | +3.4 mph |
| 120 mph | 123.7 mph | +3.7 mph |
What This Swap Means
Wider tires (245/45R19): 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.
Shorter sidewall: The 2.2mm 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 10.4mm, providing slightly better approach angles for off-road driving and speed bump clearance.