225/55R18 vs 245/50R19Tire Size Comparison

Use Caution

The 3.3% diameter difference exceeds 3% and may affect speedometer accuracy.

225/55R18705mm dia245/50R19728mm dia+11.4mm

Comparison Details

Overall Diameter704.7 vs 727.6 mm (+22.9 mm)
Diameter Difference+3.25%
Section Width225 vs 245 mm (+20 mm)
Sidewall Height123.8 vs 122.5 mm (-1.3 mm)
Circumference2213.9 vs 2285.8 mm
Clearance Change+11.4 mm
Speedometer Error+3.25%
Revs/Mile727 vs 704

Speedometer Correction

When switching from 225/55R18 to 245/50R19, your speedometer will differ from actual speed.

SpeedometerActual SpeedDifference
30 km/h31.0 km/h+1.0 km/h
40 km/h41.3 km/h+1.3 km/h
50 km/h51.6 km/h+1.6 km/h
60 km/h61.9 km/h+1.9 km/h
70 km/h72.3 km/h+2.3 km/h
80 km/h82.6 km/h+2.6 km/h
90 km/h92.9 km/h+2.9 km/h
100 km/h103.2 km/h+3.2 km/h
110 km/h113.6 km/h+3.6 km/h
120 km/h123.9 km/h+3.9 km/h
130 km/h134.2 km/h+4.2 km/h

Vehicles Using These Sizes

Vehicles with 225/55R18

Vehicles with 245/50R19

Individual Tire Size Details

Practical Guidance

The 3.3% diameter difference between 225/55R18 and 245/50R19 exceeds the standard 3% tolerance. While physically possible, this change will cause noticeable speedometer error and may affect ABS and traction control calibration. Consult a tire professional before making this switch.

The 3% diameter tolerance is a widely accepted industry guideline referenced by the ETRTO and most vehicle manufacturers. When in doubt, consult your vehicle's owner's manual or a qualified tire professional. For U.S. tire safety standards and recalls, see the NHTSA Tire Safety page.

Frequently Asked Questions

Use Caution. The overall diameter differs by 3.25%, width changes by 20mm.

Speedometer error will be 3.25%. At an indicated 100 km/h, actual speed is about 103.3 km/h.

Ground clearance changes by +11.4mm per side.