245/60R16 vs 235/50R18

235/50R18 is 0.32 in (8.2 mm) shorter than 245/60R16, a −1.17% diameter difference. With the speedometer set for 245/60R16, an indicated 60 mph is 59.3 mph on 235/50R18.

Is this a safe swap?

Diameter difference −1.17%: within the ±3% guideline

By overall diameter alone, 235/50R18 falls inside the ±3% range commonly used as a guideline when replacing 245/60R16. 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.

245/60R16 vs 235/50R18 differences
Measurement	245/60R16	235/50R18	Difference	% diff
Overall diameter	27.57 in (700.4 mm)	27.25 in (692.2 mm)	−0.32 in (−8.2 mm)	−1.17%
Sidewall height	5.79 in (147.0 mm)	4.63 in (117.5 mm)	−1.16 in (−29.5 mm)	−20.07%
Section width	9.65 in (245.0 mm)	9.25 in (235.0 mm)	−0.39 in (−10.0 mm)	−4.08%
Circumference	86.63 in (2,200.4 mm)	85.61 in (2,174.6 mm)	−1.01 in (−25.8 mm)	−1.17%
Revolutions per mile	731	740	+9	+1.18%

True speed with the speedometer calibrated for 245/60R16
Indicated	Actual on 245/60R16	Actual on 235/50R18	Difference
30 mph	30.0 mph	29.6 mph	−0.4 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: 235/50R18 lowers the vehicle by 0.16 in (4.1 mm) at the axle (half the −8.2 mm diameter difference).

235/50R18 is 0.32 in shorter than 245/60R16 and 10 mm narrower, a 1.17% difference in overall diameter.

With the speedometer calibrated for 245/60R16, an indicated 60 mph is actually 59.3 mph on 235/50R18, and revolutions per mile change from 731 to 740.

235/50R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 245/60R16.

Size pages

Other comparisons with 245/60R16

Other comparisons with 235/50R18

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