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265/70R17 vs 285/70R17 Tires: Size Difference
The 285/70R17 is 1.1 inches taller than the 265/70R17 (32.7 in against 31.6 in, +3.5%). At a displayed 60 mph on the speedometer you are really doing 62.1 mph. Edit either size below to compare something else.
3.5% taller overall: more than the common 3% guideline. Expect a clear speedometer and odometer difference, and have a tire shop check the fit.
| Measure | Current 265/70R17 | New 285/70R17 | Difference |
|---|---|---|---|
| Overall diameter | 31.6 in (803 mm) | 32.7 in (831 mm) | +1.1 in (+3.5%) |
| Section width | 10.4 in (265 mm) | 11.2 in (285 mm) | +0.8 in (+20 mm) |
| Sidewall height | 7.3 in (186 mm) | 7.9 in (200 mm) | +0.6 in (+14 mm) |
| Circumference | 99.3 in | 102.8 in | +3.5 in (+3.5%) |
| Revolutions per mile | 638 | 617 | -22 (-3.4%) |
| Rim diameter | 17 in | 17 in | 0 in |
Ground clearance changes by about +0.6 in (+14 mm) at the axle, before load and tire flex.
| Speedometer shows (mph) | 30 | 45 | 60 | 70 | 80 |
|---|---|---|---|---|---|
| Actual speed (mph) | 31.0 | 46.6 | 62.1 | 72.4 | 82.8 |
| Speedometer shows (km/h) | 50 | 80 | 100 | 120 |
|---|---|---|---|---|
| Actual speed (km/h) | 51.7 | 82.8 | 103.5 | 124.2 |
Assumes the speedometer is accurate on the current size and reads from wheel rotation. Real speedometers can read a little high or low.
Estimates from the size codes only. This does not check whether the new size fits, rubs or is safe on your vehicle; ask a tire shop before you buy.
What changes between 265/70R17 and 285/70R17
- Diameter: 31.6 in becomes 32.7 in (+1.1 in, +3.5%). 3.5% taller overall: more than the common 3% guideline. Expect a clear speedometer and odometer difference, and have a tire shop check the fit.
- Width: 265 mm (10.4 in) becomes 285 mm (11.2 in), a change of +20 mm.
- Sidewall: 186 mm (7.3 in) becomes 200 mm (7.9 in). A taller sidewall rides softer; a shorter one steers sharper.
- Revolutions per mile: 638 becomes 617, so the wheel turns 22 fewer times for every mile.
- Rim: 17 in and 17 in (the same wheel size).
Speedometer and odometer
With the 285/70R17 fitted and a speedometer set up for the 265/70R17, the dial no longer matches the road. The actual speed is the displayed speed multiplied by 32.7 / 31.6 = 1.035. The speedometer will read low by about 3.5% and the odometer will under-count distance by the same amount. Over 10,000 displayed miles you would really cover 10349 miles.
These figures assume the speedometer was accurate on the 265/70R17. A recalibration by a dealer or tuner can bring the dial back in line if the gap bothers you.
Will 285/70R17 fit instead of 265/70R17?
This page works out numbers from the size codes; it does not know your vehicle. Before you buy, check:
- The tire placard on the driver's door jamb for the approved sizes and the minimum load index and speed rating.
- Whether your wheel width suits a 285 mm tire. Every tire has an approved rim-width range.
- Clearance at full steering lock and over bumps, including the fender liner and suspension parts.
- If you change rim size, that brake calipers clear the new wheel.
The guide to reading a tire size explains every part of the code, and the pages for 265/70R17 and 285/70R17 give each size on its own.
More tire size comparisons
265/70R17 vs 285/70R17 FAQ
Is 285/70R17 bigger than 265/70R17?
Yes. The 285/70R17 is 32.7 inches tall against 31.6 inches for the 265/70R17, a difference of +1.1 inches (+3.5%). It is 20 mm wider than the 265/70R17.
How much will my speedometer be off going from 265/70R17 to 285/70R17?
If the speedometer is accurate on the 265/70R17, then at a displayed 60 mph you are doing 62.1 mph on the 285/70R17, and at a displayed 100 km/h you are doing 103.5 km/h. The odometer will differ by the same 3.5%.
Is the difference between 265/70R17 and 285/70R17 within the 3% rule?
No. The overall diameter differs by 3.5%, and the common guideline is about 3%. Staying within it keeps the speedometer error small but does not guarantee the tire will fit.
Will 285/70R17 rub where 265/70R17 does not?
That depends on your vehicle. The 285/70R17 is 20 mm wider and its sidewall is 14 mm taller. Wheel offset, wheel width, suspension and fender liners decide whether it rubs, so ask a tire shop.