215/65R17 vs 235/60R18Tire Size Comparison

Use Caution

The 3.9% diameter difference exceeds 3% and may affect speedometer accuracy.

215/65R17711mm dia235/60R18739mm dia+14.0mm

Comparison Details

Overall Diameter711.3 vs 739.2 mm (+27.9 mm)
Diameter Difference+3.92%
Section Width215 vs 235 mm (+20 mm)
Sidewall Height139.8 vs 141.0 mm (+1.2 mm)
Circumference2234.6 vs 2322.3 mm
Clearance Change+14.0 mm
Speedometer Error+3.92%
Revs/Mile720 vs 693

Speedometer Correction

When switching from 215/65R17 to 235/60R18, your speedometer will differ from actual speed.

SpeedometerActual SpeedDifference
30 km/h31.2 km/h+1.2 km/h
40 km/h41.6 km/h+1.6 km/h
50 km/h52.0 km/h+2.0 km/h
60 km/h62.4 km/h+2.4 km/h
70 km/h72.7 km/h+2.7 km/h
80 km/h83.1 km/h+3.1 km/h
90 km/h93.5 km/h+3.5 km/h
100 km/h103.9 km/h+3.9 km/h
110 km/h114.3 km/h+4.3 km/h
120 km/h124.7 km/h+4.7 km/h
130 km/h135.1 km/h+5.1 km/h

Vehicles Using These Sizes

Vehicles with 215/65R17

Vehicles with 235/60R18

Individual Tire Size Details

Practical Guidance

The 3.9% diameter difference between 215/65R17 and 235/60R18 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 3.92%, width changes by 20mm.

Speedometer error will be 3.92%. At an indicated 100 km/h, actual speed is about 103.9 km/h.

Ground clearance changes by +14.0mm per side.