215/60R17 vs 265/45R18

265/45R18 is 0.23 in (5.9 mm) taller than 215/60R17, a +0.86% diameter difference. With the speedometer set for 215/60R17, an indicated 60 mph is 60.5 mph on 265/45R18.

Is this a safe swap?

Diameter difference +0.86%: under 1%

By overall diameter alone, 265/45R18 is a near match for 215/60R17; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

Side profile and tread width, drawn to the same scale.

215/60R17 vs 265/45R18 differences
Measurement	215/60R17	265/45R18	Difference	% diff
Overall diameter	27.16 in (689.8 mm)	27.39 in (695.7 mm)	+0.23 in (+5.9 mm)	+0.86%
Sidewall height	5.08 in (129.0 mm)	4.69 in (119.3 mm)	−0.38 in (−9.7 mm)	−7.56%
Section width	8.46 in (215.0 mm)	10.43 in (265.0 mm)	+1.97 in (+50.0 mm)	+23.26%
Circumference	85.32 in (2,167.1 mm)	86.05 in (2,185.6 mm)	+0.73 in (+18.5 mm)	+0.86%
Revolutions per mile	743	736	−6	−0.85%

True speed with the speedometer calibrated for 215/60R17
Indicated	Actual on 215/60R17	Actual on 265/45R18	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.5 mph	+0.5 mph
75 mph	75.0 mph	75.6 mph	+0.6 mph

Ride-height change: 265/45R18 raises the vehicle by 0.12 in (3.0 mm) at the axle (half the +5.9 mm diameter difference).

265/45R18 is 0.23 in taller than 215/60R17 and 50 mm wider, a 0.86% difference in overall diameter.

With the speedometer calibrated for 215/60R17, an indicated 60 mph is actually 60.5 mph on 265/45R18, and revolutions per mile change from 743 to 736.

265/45R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 215/60R17.

Size pages

Other comparisons with 215/60R17

Other comparisons with 265/45R18

Source: Calculated from standard tire geometry formulas. Verified 2026-09-27. How these numbers are calculated.