235/70R15 vs 225/75R15

225/75R15 is 0.33 in (8.5 mm) taller than 235/70R15, a +1.20% diameter difference. With the speedometer set for 235/70R15, an indicated 60 mph is 60.7 mph on 225/75R15.

Is this a safe swap?

Diameter difference +1.20%: within the ±3% guideline

By overall diameter alone, 225/75R15 falls inside the ±3% range commonly used as a guideline when replacing 235/70R15. 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.

235/70R15 vs 225/75R15 differences
Measurement	235/70R15	225/75R15	Difference	% diff
Overall diameter	27.95 in (710.0 mm)	28.29 in (718.5 mm)	+0.33 in (+8.5 mm)	+1.20%
Sidewall height	6.48 in (164.5 mm)	6.64 in (168.8 mm)	+0.17 in (+4.3 mm)	+2.58%
Section width	9.25 in (235.0 mm)	8.86 in (225.0 mm)	−0.39 in (−10.0 mm)	−4.26%
Circumference	87.82 in (2,230.5 mm)	88.87 in (2,257.2 mm)	+1.05 in (+26.7 mm)	+1.20%
Revolutions per mile	722	713	−9	−1.18%

True speed with the speedometer calibrated for 235/70R15
Indicated	Actual on 235/70R15	Actual on 225/75R15	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.7 mph	+0.7 mph
75 mph	75.0 mph	75.9 mph	+0.9 mph

Ride-height change: 225/75R15 raises the vehicle by 0.17 in (4.3 mm) at the axle (half the +8.5 mm diameter difference).

225/75R15 is 0.33 in taller than 235/70R15 and 10 mm narrower, a 1.20% difference in overall diameter.

With the speedometer calibrated for 235/70R15, an indicated 60 mph is actually 60.7 mph on 225/75R15, and revolutions per mile change from 722 to 713.

Both sizes mount on 15-inch wheels.

Size pages

Other comparisons with 235/70R15

Other comparisons with 225/75R15

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