255/75R17 vs 275/70R17

275/70R17 is 0.10 in (2.5 mm) taller than 255/75R17, a +0.31% diameter difference. With the speedometer set for 255/75R17, an indicated 60 mph is 60.2 mph on 275/70R17.

Is this a safe swap?

Diameter difference +0.31%: under 1%

By overall diameter alone, 275/70R17 is a near match for 255/75R17; the speedometer changes by less than 1%. 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.

255/75R17 vs 275/70R17 differences
Measurement	255/75R17	275/70R17	Difference	% diff
Overall diameter	32.06 in (814.3 mm)	32.16 in (816.8 mm)	+0.10 in (+2.5 mm)	+0.31%
Sidewall height	7.53 in (191.3 mm)	7.58 in (192.5 mm)	+0.05 in (+1.3 mm)	+0.65%
Section width	10.04 in (255.0 mm)	10.83 in (275.0 mm)	+0.79 in (+20.0 mm)	+7.84%
Circumference	100.72 in (2,558.2 mm)	101.03 in (2,566.1 mm)	+0.31 in (+7.9 mm)	+0.31%
Revolutions per mile	629	627	−2	−0.31%

True speed with the speedometer calibrated for 255/75R17
Indicated	Actual on 255/75R17	Actual on 275/70R17	Difference
30 mph	30.0 mph	30.1 mph	+0.1 mph
60 mph	60.0 mph	60.2 mph	+0.2 mph
75 mph	75.0 mph	75.2 mph	+0.2 mph

Ride-height change: 275/70R17 raises the vehicle by 0.05 in (1.3 mm) at the axle (half the +2.5 mm diameter difference).

275/70R17 is 0.10 in taller than 255/75R17 and 20 mm wider, a 0.31% difference in overall diameter.

With the speedometer calibrated for 255/75R17, an indicated 60 mph is actually 60.2 mph on 275/70R17, and revolutions per mile change from 629 to 627.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 255/75R17

Other comparisons with 275/70R17

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