TireSizesFinder

255/85R16 vs 285/70R17

285/70R17 is 0.36 in (9.1 mm) shorter than 255/85R16, a −1.08% diameter difference. With the speedometer set for 255/85R16, an indicated 60 mph is 59.3 mph on 285/70R17.

Is this a safe swap?

Diameter difference −1.08%: within the ±3% guideline

By overall diameter alone, 285/70R17 falls inside the ±3% range commonly used as a guideline when replacing 255/85R16. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.

To-scale drawing: 255/85R16 (33.07 in) vs 285/70R17 (32.71 in)255/85R1633.07 in × 10.04 in285/70R1732.71 in × 11.22 in
Side profile and tread width, drawn to the same scale.
255/85R16 vs 285/70R17 differences
Measurement255/85R16285/70R17Difference% diff
Overall diameter33.07 in (839.9 mm)32.71 in (830.8 mm)−0.36 in (−9.1 mm)−1.08%
Sidewall height8.53 in (216.8 mm)7.85 in (199.5 mm)−0.68 in (−17.2 mm)−7.96%
Section width10.04 in (255.0 mm)11.22 in (285.0 mm)+1.18 in (+30.0 mm)+11.76%
Circumference103.88 in (2,638.6 mm)102.76 in (2,610.0 mm)−1.13 in (−28.6 mm)−1.08%
Revolutions per mile610617+7+1.10%
True speed with the speedometer calibrated for 255/85R16
IndicatedActual on 255/85R16Actual on 285/70R17Difference
30 mph30.0 mph29.7 mph−0.3 mph
60 mph60.0 mph59.3 mph−0.7 mph
75 mph75.0 mph74.2 mph−0.8 mph

Ride-height change: 285/70R17 lowers the vehicle by 0.18 in (4.6 mm) at the axle (half the −9.1 mm diameter difference).

285/70R17 is 0.36 in shorter than 255/85R16 and 30 mm wider, a 1.08% difference in overall diameter.

With the speedometer calibrated for 255/85R16, an indicated 60 mph is actually 59.3 mph on 285/70R17, and revolutions per mile change from 610 to 617.

285/70R17 mounts on a 17-inch wheel, a plus-1 fitment from the 16-inch wheel of 255/85R16.

Size pages

Other comparisons with 255/85R16

Other comparisons with 285/70R17

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