TireSizesFinder

215/45R17 vs 235/35R18

235/35R18 is 0.14 in (3.6 mm) shorter than 215/45R17, a −0.58% diameter difference. With the speedometer set for 215/45R17, an indicated 60 mph is 59.7 mph on 235/35R18.

Is this a safe swap?

Diameter difference −0.58%: under 1%

By overall diameter alone, 235/35R18 is a near match for 215/45R17; 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: 215/45R17 (24.62 in) vs 235/35R18 (24.48 in)215/45R1724.62 in × 8.46 in235/35R1824.48 in × 9.25 in
Side profile and tread width, drawn to the same scale.
215/45R17 vs 235/35R18 differences
Measurement215/45R17235/35R18Difference% diff
Overall diameter24.62 in (625.3 mm)24.48 in (621.7 mm)−0.14 in (−3.6 mm)−0.58%
Sidewall height3.81 in (96.8 mm)3.24 in (82.3 mm)−0.57 in (−14.5 mm)−14.99%
Section width8.46 in (215.0 mm)9.25 in (235.0 mm)+0.79 in (+20.0 mm)+9.30%
Circumference77.34 in (1,964.4 mm)76.89 in (1,953.1 mm)−0.45 in (−11.3 mm)−0.58%
Revolutions per mile819824+5+0.58%
True speed with the speedometer calibrated for 215/45R17
IndicatedActual on 215/45R17Actual on 235/35R18Difference
30 mph30.0 mph29.8 mph−0.2 mph
60 mph60.0 mph59.7 mph−0.3 mph
75 mph75.0 mph74.6 mph−0.4 mph

Ride-height change: 235/35R18 lowers the vehicle by 0.07 in (1.8 mm) at the axle (half the −3.6 mm diameter difference).

235/35R18 is 0.14 in shorter than 215/45R17 and 20 mm wider, a 0.58% difference in overall diameter.

With the speedometer calibrated for 215/45R17, an indicated 60 mph is actually 59.7 mph on 235/35R18, and revolutions per mile change from 819 to 824.

235/35R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 215/45R17.

Size pages

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