TireSizesFinder

205/40R17 vs 215/35R18

215/35R18 is 0.47 in (11.9 mm) taller than 205/40R17, a +2.00% diameter difference. With the speedometer set for 205/40R17, an indicated 60 mph is 61.2 mph on 215/35R18.

Is this a safe swap?

Diameter difference +2.00%: within the ±3% guideline

By overall diameter alone, 215/35R18 falls inside the ±3% range commonly used as a guideline when replacing 205/40R17. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 205/40R17 (23.46 in) vs 215/35R18 (23.93 in)205/40R1723.46 in × 8.07 in215/35R1823.93 in × 8.46 in
Side profile and tread width, drawn to the same scale.
205/40R17 vs 215/35R18 differences
Measurement205/40R17215/35R18Difference% diff
Overall diameter23.46 in (595.8 mm)23.93 in (607.7 mm)+0.47 in (+11.9 mm)+2.00%
Sidewall height3.23 in (82.0 mm)2.96 in (75.3 mm)−0.27 in (−6.7 mm)−8.23%
Section width8.07 in (205.0 mm)8.46 in (215.0 mm)+0.39 in (+10.0 mm)+4.88%
Circumference73.69 in (1,871.8 mm)75.16 in (1,909.1 mm)+1.47 in (+37.4 mm)+2.00%
Revolutions per mile860843−17−1.96%
True speed with the speedometer calibrated for 205/40R17
IndicatedActual on 205/40R17Actual on 215/35R18Difference
30 mph30.0 mph30.6 mph+0.6 mph
60 mph60.0 mph61.2 mph+1.2 mph
75 mph75.0 mph76.5 mph+1.5 mph

Ride-height change: 215/35R18 raises the vehicle by 0.23 in (6.0 mm) at the axle (half the +11.9 mm diameter difference).

215/35R18 is 0.47 in taller than 205/40R17 and 10 mm wider, a 2.00% difference in overall diameter.

With the speedometer calibrated for 205/40R17, an indicated 60 mph is actually 61.2 mph on 215/35R18, and revolutions per mile change from 860 to 843.

215/35R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 205/40R17.

Size pages

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