235/75R16 vs 245/60R18

245/60R18 is 0.30 in (7.7 mm) shorter than 235/75R16, a −1.01% diameter difference. With the speedometer set for 235/75R16, an indicated 60 mph is 59.4 mph on 245/60R18.

Is this a safe swap?

Diameter difference −1.01%: within the ±3% guideline

By overall diameter alone, 245/60R18 falls inside the ±3% range commonly used as a guideline when replacing 235/75R16. 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.

235/75R16 vs 245/60R18 differences
Measurement	235/75R16	245/60R18	Difference	% diff
Overall diameter	29.88 in (758.9 mm)	29.57 in (751.2 mm)	−0.30 in (−7.7 mm)	−1.01%
Sidewall height	6.94 in (176.3 mm)	5.79 in (147.0 mm)	−1.15 in (−29.2 mm)	−16.60%
Section width	9.25 in (235.0 mm)	9.65 in (245.0 mm)	+0.39 in (+10.0 mm)	+4.26%
Circumference	93.86 in (2,384.2 mm)	92.91 in (2,360.0 mm)	−0.95 in (−24.2 mm)	−1.01%
Revolutions per mile	675	682	+7	+1.03%

True speed with the speedometer calibrated for 235/75R16
Indicated	Actual on 235/75R16	Actual on 245/60R18	Difference
30 mph	30.0 mph	29.7 mph	−0.3 mph
60 mph	60.0 mph	59.4 mph	−0.6 mph
75 mph	75.0 mph	74.2 mph	−0.8 mph

Ride-height change: 245/60R18 lowers the vehicle by 0.15 in (3.8 mm) at the axle (half the −7.7 mm diameter difference).

245/60R18 is 0.30 in shorter than 235/75R16 and 10 mm wider, a 1.01% difference in overall diameter.

With the speedometer calibrated for 235/75R16, an indicated 60 mph is actually 59.4 mph on 245/60R18, and revolutions per mile change from 675 to 682.

245/60R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 235/75R16.

Size pages

Other comparisons with 235/75R16

Other comparisons with 245/60R18

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