Is 285/70R17 bigger than 275/70R17?

285/70R17 is 0.55 inches taller and 10 mm wider. In overall diameter that is +1.71%, which stays inside the ±3% rule of thumb for a substitution.

How much will 285/70R17 throw off my speedometer?

Every reading scales by 1.01714. An indicated 60 mph becomes 61.0 mph, and every 100 miles on the odometer is really 101.7 miles.

How much does 285/70R17 change ground clearance over 275/70R17?

The axle centerline moves by 0.28 inches — half the diameter change, because half the extra height sits below the hub and half above it.

Will 285/70R17 fit where 275/70R17 fits?

Nothing derived from the size code can answer that. Clearance depends on wheel offset, suspension travel and body dimensions that no tire size contains. This page tells you exactly what changes dimensionally, which is the part that can be calculated.

275/70R17 vs 285/70R17

285/70R17 is +0.55″ in overall diameter and +10 mm in section width against 275/70R17 — a diameter change of +1.71%, which stays inside the ±3% substitution rule. An indicated 60 mph would really be 61.0 mph.

Within 3%

Every dimension

Difference between 275/70R17 and 285/70R17
Dimension	275/70R17 → 285/70R17	Change
Overall diameter	32.16″ → 32.71″	+0.55″ (+1.71%)
Section width	275 mm → 285 mm	+10 mm (+3.64%)
Sidewall height	192.5 mm → 199.5 mm	+7.0 mm
Rolling circumference	101.03″ → 102.76″	+1.73″
Revolutions per mile	627.2 → 616.6	−10.6
Axle height / clearance	16.08″ → 16.35″	+0.28″

275/70R17275 mm

285/70R17285 mm

275/70R17 32.16″285/70R17 32.71″

Which is taller, 275/70R17 or 285/70R17?

285/70R17 is the taller of the two, at 32.71″ against 32.16″. The gap is 0.55 inches, or 14.0 mm.

Both are metric sizes, so neither states its height directly. Both figures below are derived from the section width, aspect ratio and wheel diameter in the code. 275/70R17 is 275 mm wide with a 192.5 mm sidewall on a 17″ wheel; 285/70R17 is 285 mm wide with a 199.5 mm sidewall on a 17″ wheel.

What the speedometer will read

Indicated versus actual speed after the size change
Speedometer reads	Actual speed	Error
25 mph	25.4 mph	+0.4 mph
40 mph	40.7 mph	+0.7 mph
55 mph	55.9 mph	+0.9 mph
60 mph	61.0 mph	+1.0 mph
70 mph	71.2 mph	+1.2 mph
80 mph	81.4 mph	+1.4 mph

Fitting 285/70R17 in place of 275/70R17 multiplies every speed and distance reading by 1.01714. Over 10,000 indicated miles the odometer is out by +171 miles.

Effective gearing moves by the same proportion. A vehicle with 3.73 axles running 275/70R17 would need 3.79 to keep the same engine speed on 285/70R17. Work it out for your own axle ratio.

Full specification of each size

275/70R17

Derived dimensions for 275/70R17
Dimension	Metric	Imperial
Section width	275.0 mm	10.83″
Sidewall height	192.5 mm	7.58″
Wheel diameter	431.8 mm	17.0″
Overall diameter	816.8 mm	32.16″
Rolling circumference	2,566.1 mm	101.03″
Revolutions per mile	389.7 / km	627.2 / mile
Measuring rim (estimate)	216 mm	8.5″

285/70R17

Derived dimensions for 285/70R17
Dimension	Metric	Imperial
Section width	285.0 mm	11.22″
Sidewall height	199.5 mm	7.85″
Wheel diameter	431.8 mm	17.0″
Overall diameter	830.8 mm	32.71″
Rolling circumference	2,610.0 mm	102.76″
Revolutions per mile	383.1 / km	616.6 / mile
Measuring rim (estimate)	216 mm	8.5″

Rim widths differ too: 275/70R17 is designed for 8″–9.5″ and 285/70R17 for 8″–9.5″. They share a measuring rim, so one wheel can usually carry either.

Can you swap one for the other?

Inside the ±3% rule

The diameter difference of +1.71% is within the ±3% that fitters use as the boundary for a substitution, so the speedometer, odometer and wheel-speed-derived systems stay close enough to calibration. The section width difference of +10 mm is a separate question and is the one that decides whether it rubs.

Neither figure says anything about physical fitment. Whether 285/70R17 clears the strut, the fender liner and the steering stops depends on wheel offset and suspension geometry that a size code does not encode. For maintenance rather than sizing, Car Basics covers tire care.