TireSizesFinder

225/40R17 vs 215/35R18

215/35R18 is 0.16 in (4.1 mm) shorter than 225/40R17, a −0.67% diameter difference. With the speedometer set for 225/40R17, an indicated 60 mph is 59.6 mph on 215/35R18.

Is this a safe swap?

Diameter difference −0.67%: under 1%

By overall diameter alone, 215/35R18 is a near match for 225/40R17; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 225/40R17 (24.09 in) vs 215/35R18 (23.93 in)225/40R1724.09 in × 8.86 in215/35R1823.93 in × 8.46 in
Side profile and tread width, drawn to the same scale.
225/40R17 vs 215/35R18 differences
Measurement225/40R17215/35R18Difference% diff
Overall diameter24.09 in (611.8 mm)23.93 in (607.7 mm)−0.16 in (−4.1 mm)−0.67%
Sidewall height3.54 in (90.0 mm)2.96 in (75.3 mm)−0.58 in (−14.7 mm)−16.39%
Section width8.86 in (225.0 mm)8.46 in (215.0 mm)−0.39 in (−10.0 mm)−4.44%
Circumference75.67 in (1,922.0 mm)75.16 in (1,909.1 mm)−0.51 in (−12.9 mm)−0.67%
Revolutions per mile837843+6+0.67%
True speed with the speedometer calibrated for 225/40R17
IndicatedActual on 225/40R17Actual on 215/35R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.5 mph−0.5 mph

Ride-height change: 215/35R18 lowers the vehicle by 0.08 in (2.0 mm) at the axle (half the −4.1 mm diameter difference).

215/35R18 is 0.16 in shorter than 225/40R17 and 10 mm narrower, a 0.67% difference in overall diameter.

With the speedometer calibrated for 225/40R17, an indicated 60 mph is actually 59.6 mph on 215/35R18, and revolutions per mile change from 837 to 843.

215/35R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 225/40R17.

Size pages

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Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.