245/75R17 vs 235/80R17

235/80R17 is 0.33 in (8.5 mm) taller than 245/75R17, a +1.06% diameter difference. With the speedometer set for 245/75R17, an indicated 60 mph is 60.6 mph on 235/80R17.

Is this a safe swap?

Diameter difference +1.06%: within the ±3% guideline

By overall diameter alone, 235/80R17 falls inside the ±3% range commonly used as a guideline when replacing 245/75R17. 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.

245/75R17 vs 235/80R17 differences
Measurement	245/75R17	235/80R17	Difference	% diff
Overall diameter	31.47 in (799.3 mm)	31.80 in (807.8 mm)	+0.33 in (+8.5 mm)	+1.06%
Sidewall height	7.23 in (183.8 mm)	7.40 in (188.0 mm)	+0.17 in (+4.3 mm)	+2.31%
Section width	9.65 in (245.0 mm)	9.25 in (235.0 mm)	−0.39 in (−10.0 mm)	−4.08%
Circumference	98.86 in (2,511.1 mm)	99.91 in (2,537.8 mm)	+1.05 in (+26.7 mm)	+1.06%
Revolutions per mile	641	634	−7	−1.05%

True speed with the speedometer calibrated for 245/75R17
Indicated	Actual on 245/75R17	Actual on 235/80R17	Difference
30 mph	30.0 mph	30.3 mph	+0.3 mph
60 mph	60.0 mph	60.6 mph	+0.6 mph
75 mph	75.0 mph	75.8 mph	+0.8 mph

Ride-height change: 235/80R17 raises the vehicle by 0.17 in (4.3 mm) at the axle (half the +8.5 mm diameter difference).

235/80R17 is 0.33 in taller than 245/75R17 and 10 mm narrower, a 1.06% difference in overall diameter.

With the speedometer calibrated for 245/75R17, an indicated 60 mph is actually 60.6 mph on 235/80R17, and revolutions per mile change from 641 to 634.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 245/75R17

Other comparisons with 235/80R17

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