17-inch rim · tyre size comparison

265/70 R17 vs 285/65 R17

285/65 R17 and 265/70 R17 are effectively the same height: 285/65 R17 is 0.5 mm shorter in overall diameter, a -0.06% difference. That is well inside the ±3% limit commonly used to screen a tire size change; it is a nominal calculation, not a fitment approval.

Diameter difference
-0.5 mm
-0.02 in · -0.06%
Indicated 70 mph
70 mph
Actual speed on 285/65 R17, if the speedometer was accurate on 265/70 R17.
Sidewall height
-0.25 mm
185.5 mm to 185.25 mm.
Compare in the calculator265/70 R17 size guide285/65 R17 size guideSpeedometerWhat changes

Dimensions side by side

265/70 R17 and 285/65 R17 dimensions
Measurement265/70 R17285/65 R17Difference
Overall diameter802.8 mm31.61 in802.3 mm31.59 in-0.5 mm (-0.06%)-0.02 in
Section width265 mm10.43 in285 mm11.22 in+20 mm+0.79 in
Sidewall height185.5 mm7.3 in185.25 mm7.29 in-0.25 mm-0.01 in
Circumference2,522.07 mm99.29 in2,520.5 mm99.23 in-1.57 mm-0.06 in
Rim diameter431.8 mm17 in431.8 mm17 in0 mm0 in
Revolutions per mile638.1638.5+0.4
Revolutions per km396.5396.75+0.25
265/70 R17285/65 R17
Nominal diameters at the same scale. The inner circle is the rim.

Calculated from the nominal size codes, without load or tread wear. Real tyres vary by model, rim width and pressure, so the exact tyre's published dimensions take priority.

Speedometer with 285/65 R17

If the speedometer was accurate on 265/70 R17, fitting 285/65 R17 means the car is travelling 0.06% slower than it shows, and the odometer over-records distance by about the same amount.

Indicated speed versus calculated road speed on 285/65 R17
Speedometer showsActual on 285/65 R17Difference
30 mph29.98 mph-0.02 mph
50 mph49.97 mph-0.03 mph
60 mph59.96 mph-0.04 mph
70 mph69.96 mph-0.04 mph
50 km/h49.97 km/h-0.03 km/h
100 km/h99.94 km/h-0.06 km/h

UN ECE Regulation 39, used in the UK and EU, does not allow a speedometer to show less than the true speed, so many read slightly high from the factory. A shorter tyre adds to it. Calibration varies by car; these figures are the tyre-size effect only.

What changes from 265/70 R17 to 285/65 R17

  • Wheels

    Both fit 17-inch wheels. Our rim-width starting estimate is 7.5 to 8.5 inches for 265/70 R17 and 8 to 9 inches for 285/65 R17, so a 8 to 8.5-inch wheel sits in both ranges. The exact tyre's approved rim range takes priority.

  • Sidewall and ride comfort

    Sidewall height differs by only 0.25 mm (185.5 vs 185.25 mm), so ride comfort and steering feel will depend more on the tyre model and pressures than on the size.

  • Contact width

    285/65 R17 is 20 mm wider in nominal section width (7.5%). A wider tyre usually puts a wider, shorter contact patch on the road, which can help dry grip, but it may follow ruts more, clear standing water less readily and add some rolling resistance.

  • Wheel well clearance

    Ride height is effectively unchanged. On the same wheel width and offset, each sidewall moves about 10 mm further out towards the arch lip and further in towards the suspension. Check clearance at full steering lock and full suspension compression, especially on a lowered car.

  • Gearing

    Effective gearing changes by +0.06%, too little to notice from the driver's seat.

  • ABS, stability control and AWD

    These systems compare wheel speeds. Fit the same size on both ends of an axle, and follow the car maker's rolling-circumference limits, which can be much tighter than 3%.

General tendencies from the nominal numbers, not a test of any tyre. Load index, speed rating, tyre construction and the car's approved sizes matter more than these rules of thumb.

Cars in our guides using these sizes

More comparisons

Questions

Can I use 285/65 R17 instead of 265/70 R17?

Both fit 17-inch wheels. The diameter difference is -0.06%, well inside the ±3% screening limit. That does not approve fitment: check the car maker's approved sizes, load index, speed rating, rim width and clearance first.

How much bigger is 285/65 R17 than 265/70 R17?

Overall diameter is 0.5 mm (0.02 in) smaller: 802.3 vs 802.8 mm. Section width is 20 mm wider, and the sidewall is 0.25 mm shorter. These are nominal figures; real tyres vary by model and rim width.

Will 285/65 R17 change my speedometer reading?

Yes, by 0.06%. If the speedometer was accurate on 265/70 R17, an indicated 60 mph would be about 60 mph on 285/65 R17, and an indicated 100 km/h about 99.9 km/h. You would be going slower than the speedometer shows.

Which is better, 265/70 R17 or 285/65 R17?

Neither in general. 285/65 R17 is wider, which can help dry grip; the narrower size is usually better in standing water and snow. The size listed for your car's trim, on its placard or in the handbook, is the safe default.

Check the exact tyre

Size codes give nominal dimensions. Before buying, confirm the size is approved for your car and check the exact tyre's load and speed ratings and published dimensions.