235/60R18 vs 245/60R18

245/60R18 is 0.47 in (12.0 mm) taller than 235/60R18, a +1.62% diameter difference. With the speedometer set for 235/60R18, an indicated 60 mph is 61.0 mph on 245/60R18.

Is this a safe swap?

Diameter difference +1.62%: within the ±3% guideline

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

235/60R18 vs 245/60R18 differences
Measurement	235/60R18	245/60R18	Difference	% diff
Overall diameter	29.10 in (739.2 mm)	29.57 in (751.2 mm)	+0.47 in (+12.0 mm)	+1.62%
Sidewall height	5.55 in (141.0 mm)	5.79 in (147.0 mm)	+0.24 in (+6.0 mm)	+4.26%
Section width	9.25 in (235.0 mm)	9.65 in (245.0 mm)	+0.39 in (+10.0 mm)	+4.26%
Circumference	91.43 in (2,322.3 mm)	92.91 in (2,360.0 mm)	+1.48 in (+37.7 mm)	+1.62%
Revolutions per mile	693	682	−11	−1.60%

True speed with the speedometer calibrated for 235/60R18
Indicated	Actual on 235/60R18	Actual on 245/60R18	Difference
30 mph	30.0 mph	30.5 mph	+0.5 mph
60 mph	60.0 mph	61.0 mph	+1.0 mph
75 mph	75.0 mph	76.2 mph	+1.2 mph

Ride-height change: 245/60R18 raises the vehicle by 0.24 in (6.0 mm) at the axle (half the +12.0 mm diameter difference).

245/60R18 is 0.47 in taller than 235/60R18 and 10 mm wider, a 1.62% difference in overall diameter.

With the speedometer calibrated for 235/60R18, an indicated 60 mph is actually 61.0 mph on 245/60R18, and revolutions per mile change from 693 to 682.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 235/60R18

Other comparisons with 245/60R18

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