225/40R18 vs 245/35R19Tire Size Comparison

Safe

The 2.6% diameter difference is within the accepted 3% tolerance.

225/40R18637mm dia245/35R19654mm dia+8.4mm

Comparison Details

Overall Diameter637.2 vs 654.1 mm (+16.9 mm)
Diameter Difference+2.65%
Section Width225 vs 245 mm (+20 mm)
Sidewall Height90.0 vs 85.8 mm (-4.2 mm)
Circumference2001.8 vs 2054.9 mm
Clearance Change+8.4 mm
Speedometer Error+2.65%
Revs/Mile804 vs 783

Speedometer Correction

When switching from 225/40R18 to 245/35R19, your speedometer will differ from actual speed.

SpeedometerActual SpeedDifference
30 km/h30.8 km/h+0.8 km/h
40 km/h41.1 km/h+1.1 km/h
50 km/h51.3 km/h+1.3 km/h
60 km/h61.6 km/h+1.6 km/h
70 km/h71.9 km/h+1.9 km/h
80 km/h82.1 km/h+2.1 km/h
90 km/h92.4 km/h+2.4 km/h
100 km/h102.7 km/h+2.7 km/h
110 km/h112.9 km/h+2.9 km/h
120 km/h123.2 km/h+3.2 km/h
130 km/h133.4 km/h+3.4 km/h

Vehicles Using These Sizes

Vehicles with 225/40R18

Vehicles with 245/35R19

Individual Tire Size Details

Practical Guidance

Switching from 225/40R18 to 245/35R19 is within the industry-accepted 3% diameter tolerance. Your speedometer, ABS, and traction control should function normally. Note: these sizes require different rim diameters (18" vs 19"), so you will need different wheels.

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

Safe. The overall diameter differs by 2.65%, width changes by 20mm.

Speedometer error will be 2.65%. At an indicated 100 km/h, actual speed is about 102.7 km/h.

Ground clearance changes by +8.4mm per side.