275/70R17 vs 305/65R17

305/65R17 is 0.45 in (11.5 mm) taller than 275/70R17, a +1.41% diameter difference. With the speedometer set for 275/70R17, an indicated 60 mph is 60.8 mph on 305/65R17.

Is this a safe swap?

Diameter difference +1.41%: within the ±3% guideline

By overall diameter alone, 305/65R17 falls inside the ±3% range commonly used as a guideline when replacing 275/70R17. 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.

275/70R17 vs 305/65R17 differences
Measurement	275/70R17	305/65R17	Difference	% diff
Overall diameter	32.16 in (816.8 mm)	32.61 in (828.3 mm)	+0.45 in (+11.5 mm)	+1.41%
Sidewall height	7.58 in (192.5 mm)	7.81 in (198.3 mm)	+0.23 in (+5.8 mm)	+2.99%
Section width	10.83 in (275.0 mm)	12.01 in (305.0 mm)	+1.18 in (+30.0 mm)	+10.91%
Circumference	101.03 in (2,566.1 mm)	102.45 in (2,602.2 mm)	+1.42 in (+36.1 mm)	+1.41%
Revolutions per mile	627	618	−9	−1.39%

True speed with the speedometer calibrated for 275/70R17
Indicated	Actual on 275/70R17	Actual on 305/65R17	Difference
30 mph	30.0 mph	30.4 mph	+0.4 mph
60 mph	60.0 mph	60.8 mph	+0.8 mph
75 mph	75.0 mph	76.1 mph	+1.1 mph

Ride-height change: 305/65R17 raises the vehicle by 0.23 in (5.8 mm) at the axle (half the +11.5 mm diameter difference).

305/65R17 is 0.45 in taller than 275/70R17 and 30 mm wider, a 1.41% difference in overall diameter.

With the speedometer calibrated for 275/70R17, an indicated 60 mph is actually 60.8 mph on 305/65R17, and revolutions per mile change from 627 to 618.

Both sizes mount on 17-inch wheels.

Size pages

Other comparisons with 275/70R17

Other comparisons with 305/65R17

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