235/65R17 vs 235/60R18

235/60R18 is 0.07 in (1.9 mm) taller than 235/65R17, a +0.26% diameter difference. With the speedometer set for 235/65R17, an indicated 60 mph is 60.2 mph on 235/60R18.

Is this a safe swap?

Diameter difference +0.26%: under 1%

By overall diameter alone, 235/60R18 is a near match for 235/65R17; 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.

235/65R17 vs 235/60R18 differences
Measurement	235/65R17	235/60R18	Difference	% diff
Overall diameter	29.03 in (737.3 mm)	29.10 in (739.2 mm)	+0.07 in (+1.9 mm)	+0.26%
Sidewall height	6.01 in (152.8 mm)	5.55 in (141.0 mm)	−0.46 in (−11.7 mm)	−7.69%
Section width	9.25 in (235.0 mm)	9.25 in (235.0 mm)	0.00 in (0.0 mm)	0.00%
Circumference	91.19 in (2,316.3 mm)	91.43 in (2,322.3 mm)	+0.24 in (+6.0 mm)	+0.26%
Revolutions per mile	695	693	−2	−0.26%

True speed with the speedometer calibrated for 235/65R17
Indicated	Actual on 235/65R17	Actual on 235/60R18	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.2 mph	+0.2 mph
75 mph	75.0 mph	75.2 mph	+0.2 mph

Ride-height change: 235/60R18 raises the vehicle by 0.04 in (1.0 mm) at the axle (half the +1.9 mm diameter difference).

235/60R18 is 0.07 in taller than 235/65R17 and the same width, a 0.26% difference in overall diameter.

With the speedometer calibrated for 235/65R17, an indicated 60 mph is actually 60.2 mph on 235/60R18, and revolutions per mile change from 695 to 693.

235/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 235/65R17.

Size pages

Other comparisons with 235/65R17

Other comparisons with 235/60R18

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