225/60R18 vs 235/60R18

235/60R18 is 0.47 in (12.0 mm) taller than 225/60R18, a +1.65% diameter difference. With the speedometer set for 225/60R18, an indicated 60 mph is 61.0 mph on 235/60R18.

Is this a safe swap?

Diameter difference +1.65%: within the ±3% guideline

By overall diameter alone, 235/60R18 falls inside the ±3% range commonly used as a guideline when replacing 225/60R18. 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.

225/60R18 vs 235/60R18 differences
Measurement	225/60R18	235/60R18	Difference	% diff
Overall diameter	28.63 in (727.2 mm)	29.10 in (739.2 mm)	+0.47 in (+12.0 mm)	+1.65%
Sidewall height	5.31 in (135.0 mm)	5.55 in (141.0 mm)	+0.24 in (+6.0 mm)	+4.44%
Section width	8.86 in (225.0 mm)	9.25 in (235.0 mm)	+0.39 in (+10.0 mm)	+4.44%
Circumference	89.94 in (2,284.6 mm)	91.43 in (2,322.3 mm)	+1.48 in (+37.7 mm)	+1.65%
Revolutions per mile	704	693	−11	−1.62%

True speed with the speedometer calibrated for 225/60R18
Indicated	Actual on 225/60R18	Actual on 235/60R18	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: 235/60R18 raises the vehicle by 0.24 in (6.0 mm) at the axle (half the +12.0 mm diameter difference).

235/60R18 is 0.47 in taller than 225/60R18 and 10 mm wider, a 1.65% difference in overall diameter.

With the speedometer calibrated for 225/60R18, an indicated 60 mph is actually 61.0 mph on 235/60R18, and revolutions per mile change from 704 to 693.

Both sizes mount on 18-inch wheels.

Size pages

Other comparisons with 225/60R18

Other comparisons with 235/60R18

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