235/75R17 vs 265/60R18

265/60R18 is 0.36 in (9.1 mm) shorter than 235/75R17, a −1.16% diameter difference. With the speedometer set for 235/75R17, an indicated 60 mph is 59.3 mph on 265/60R18.

Is this a safe swap?

Diameter difference −1.16%: within the ±3% guideline

By overall diameter alone, 265/60R18 falls inside the ±3% range commonly used as a guideline when replacing 235/75R17. 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.

235/75R17 vs 265/60R18 differences
Measurement	235/75R17	265/60R18	Difference	% diff
Overall diameter	30.88 in (784.3 mm)	30.52 in (775.2 mm)	−0.36 in (−9.1 mm)	−1.16%
Sidewall height	6.94 in (176.3 mm)	6.26 in (159.0 mm)	−0.68 in (−17.2 mm)	−9.79%
Section width	9.25 in (235.0 mm)	10.43 in (265.0 mm)	+1.18 in (+30.0 mm)	+12.77%
Circumference	97.01 in (2,464.0 mm)	95.88 in (2,435.4 mm)	−1.13 in (−28.6 mm)	−1.16%
Revolutions per mile	653	661	+8	+1.17%

True speed with the speedometer calibrated for 235/75R17
Indicated	Actual on 235/75R17	Actual on 265/60R18	Difference
30 mph	30.0 mph	29.7 mph	−0.3 mph
60 mph	60.0 mph	59.3 mph	−0.7 mph
75 mph	75.0 mph	74.1 mph	−0.9 mph

Ride-height change: 265/60R18 lowers the vehicle by 0.18 in (4.5 mm) at the axle (half the −9.1 mm diameter difference).

265/60R18 is 0.36 in shorter than 235/75R17 and 30 mm wider, a 1.16% difference in overall diameter.

With the speedometer calibrated for 235/75R17, an indicated 60 mph is actually 59.3 mph on 265/60R18, and revolutions per mile change from 653 to 661.

265/60R18 mounts on a 18-inch wheel, a plus-1 fitment from the 17-inch wheel of 235/75R17.

Size pages

Other comparisons with 235/75R17

Other comparisons with 265/60R18

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