245/75R15 vs 235/70R17

235/70R17 is 0.48 in (12.3 mm) taller than 245/75R15, a +1.64% diameter difference. With the speedometer set for 245/75R15, an indicated 60 mph is 61.0 mph on 235/70R17.

Is this a safe swap?

Diameter difference +1.64%: within the ±3% guideline

By overall diameter alone, 235/70R17 falls inside the ±3% range commonly used as a guideline when replacing 245/75R15. 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.

245/75R15 vs 235/70R17 differences
Measurement	245/75R15	235/70R17	Difference	% diff
Overall diameter	29.47 in (748.5 mm)	29.95 in (760.8 mm)	+0.48 in (+12.3 mm)	+1.64%
Sidewall height	7.23 in (183.8 mm)	6.48 in (164.5 mm)	−0.76 in (−19.2 mm)	−10.48%
Section width	9.65 in (245.0 mm)	9.25 in (235.0 mm)	−0.39 in (−10.0 mm)	−4.08%
Circumference	92.58 in (2,351.5 mm)	94.10 in (2,390.1 mm)	+1.52 in (+38.6 mm)	+1.64%
Revolutions per mile	684	673	−11	−1.62%

True speed with the speedometer calibrated for 245/75R15
Indicated	Actual on 245/75R15	Actual on 235/70R17	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: 235/70R17 raises the vehicle by 0.24 in (6.1 mm) at the axle (half the +12.3 mm diameter difference).

235/70R17 is 0.48 in taller than 245/75R15 and 10 mm narrower, a 1.64% difference in overall diameter.

With the speedometer calibrated for 245/75R15, an indicated 60 mph is actually 61.0 mph on 235/70R17, and revolutions per mile change from 684 to 673.

235/70R17 mounts on a 17-inch wheel, a plus-2 fitment from the 15-inch wheel of 245/75R15.

Size pages

Other comparisons with 245/75R15

Other comparisons with 235/70R17

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