TireSizesFinder

305/70R16 vs 285/70R17

285/70R17 is 0.10 in (2.6 mm) shorter than 305/70R16, a −0.31% diameter difference. With the speedometer set for 305/70R16, an indicated 60 mph is 59.8 mph on 285/70R17.

Is this a safe swap?

Diameter difference −0.31%: under 1%

By overall diameter alone, 285/70R17 is a near match for 305/70R16; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 305/70R16 (32.81 in) vs 285/70R17 (32.71 in)305/70R1632.81 in × 12.01 in285/70R1732.71 in × 11.22 in
Side profile and tread width, drawn to the same scale.
305/70R16 vs 285/70R17 differences
Measurement305/70R16285/70R17Difference% diff
Overall diameter32.81 in (833.4 mm)32.71 in (830.8 mm)−0.10 in (−2.6 mm)−0.31%
Sidewall height8.41 in (213.5 mm)7.85 in (199.5 mm)−0.55 in (−14.0 mm)−6.56%
Section width12.01 in (305.0 mm)11.22 in (285.0 mm)−0.79 in (−20.0 mm)−6.56%
Circumference103.08 in (2,618.2 mm)102.76 in (2,610.0 mm)−0.32 in (−8.2 mm)−0.31%
Revolutions per mile615617+2+0.31%
True speed with the speedometer calibrated for 305/70R16
IndicatedActual on 305/70R16Actual on 285/70R17Difference
30 mph30.0 mph29.9 mph−0.1 mph
60 mph60.0 mph59.8 mph−0.2 mph
75 mph75.0 mph74.8 mph−0.2 mph

Ride-height change: 285/70R17 lowers the vehicle by 0.05 in (1.3 mm) at the axle (half the −2.6 mm diameter difference).

285/70R17 is 0.10 in shorter than 305/70R16 and 20 mm narrower, a 0.31% difference in overall diameter.

With the speedometer calibrated for 305/70R16, an indicated 60 mph is actually 59.8 mph on 285/70R17, and revolutions per mile change from 615 to 617.

285/70R17 mounts on a 17-inch wheel, a plus-1 fitment from the 16-inch wheel of 305/70R16.

Size pages

Other comparisons with 305/70R16

Other comparisons with 285/70R17

Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.