TireSizesFinder

225/65R16 vs 215/55R18

215/55R18 is 0.20 in (5.2 mm) shorter than 225/65R16, a −0.74% diameter difference. With the speedometer set for 225/65R16, an indicated 60 mph is 59.6 mph on 215/55R18.

Is this a safe swap?

Diameter difference −0.74%: under 1%

By overall diameter alone, 215/55R18 is a near match for 225/65R16; 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: 225/65R16 (27.52 in) vs 215/55R18 (27.31 in)225/65R1627.52 in × 8.86 in215/55R1827.31 in × 8.46 in
Side profile and tread width, drawn to the same scale.
225/65R16 vs 215/55R18 differences
Measurement225/65R16215/55R18Difference% diff
Overall diameter27.52 in (698.9 mm)27.31 in (693.7 mm)−0.20 in (−5.2 mm)−0.74%
Sidewall height5.76 in (146.3 mm)4.66 in (118.3 mm)−1.10 in (−28.0 mm)−19.15%
Section width8.86 in (225.0 mm)8.46 in (215.0 mm)−0.39 in (−10.0 mm)−4.44%
Circumference86.44 in (2,195.7 mm)85.80 in (2,179.3 mm)−0.64 in (−16.3 mm)−0.74%
Revolutions per mile733738+5+0.75%
True speed with the speedometer calibrated for 225/65R16
IndicatedActual on 225/65R16Actual on 215/55R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.6 mph−0.4 mph
75 mph75.0 mph74.4 mph−0.6 mph

Ride-height change: 215/55R18 lowers the vehicle by 0.10 in (2.6 mm) at the axle (half the −5.2 mm diameter difference).

215/55R18 is 0.20 in shorter than 225/65R16 and 10 mm narrower, a 0.74% difference in overall diameter.

With the speedometer calibrated for 225/65R16, an indicated 60 mph is actually 59.6 mph on 215/55R18, and revolutions per mile change from 733 to 738.

215/55R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 225/65R16.

Size pages

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