265/70R17 vs 32x11.50R17 — equivalence at the small end
The 33-inch argument, played out one size lower, where the metric tire is the one most vehicles came with.
32x11.50R17 is 0.39 in taller than 265/70R17 (1.25%) and 1.07 in wider. A speedometer calibrated for 265/70R17 would under-read by 1.25%.
Measured against each other
Overall diameter
31.61 in32.00 in+0.39 in (+1.25%)Section width
10.43 in / 265 mm11.50 in / 292 mm+1.07 in (+10.23%)Sidewall height
7.30 in7.50 in+0.20 inCircumference
99.3 in100.5 in+1.2 inRevolutions per mile
638.1630.3-7.9Ride height at the axle
——+0.20 inSpeedometer reading
——+1.25% under-read
| Dimension | 265/70R17 | 32x11.50R17 | Change |
|---|---|---|---|
| Overall diameter | 31.61 in | 32.00 in | +0.39 in (+1.25%) |
| Section width | 10.43 in / 265 mm | 11.50 in / 292 mm | +1.07 in (+10.23%) |
| Sidewall height | 7.30 in | 7.50 in | +0.20 in |
| Circumference | 99.3 in | 100.5 in | +1.2 in |
| Revolutions per mile | 638.1 | 630.3 | -7.9 |
| Ride height at the axle | — | — | +0.20 in |
| Speedometer reading | — | — | +1.25% under-read |
Calibrated for 265/70R17, running 32x11.50R17
- Dial reads 30
- 30.4 mph
- Dial reads 50
- 50.6 mph
- Dial reads 70
- 70.9 mph
- Odometer counts 100
- 101.2 mi covered
Change either size in the comparison tool, or see the full speed table in the speedometer error calculator.
Most metric-versus-flotation comparisons pit an aftermarket size against another aftermarket size. This one starts from the tire the vehicle was delivered on.
How close the metric size gets
265/70R17 works out to 31.61 in. A 32 is 32.00 in by definition. The gap is 0.39 in — 1.25% — which means the most common factory size on 17-inch wheels in North America is very nearly, but not quite, what the trade calls a 32.
Rounded to the nearest half inch it is a 31.5. In conversation it is usually called a 32, and the half-inch of licence in that is roughly the same licence people take when they call a 285/70R17 a 33.
The width gap is the bigger one
10.43 in against 11.50 in — 1.07 in, or 10.23%. As with almost every metric-to-flotation pairing, the dimension nobody checks is the one that has moved most.
The sidewalls, by contrast, are close: 7.30 in and 7.50 in. And the derived aspect ratio of 32x11.50R17 is 65, against the metric size's stated 70 — the flotation tire is the squatter of the two despite being taller.
What the change does
If the reason for the comparison is the speedometer, the answer is that the swap is invisible to it: a mile an hour light at motorway speed, and a fifth of an inch at the axle. There is nothing here that needs allowing for, and the whole of the case for the flotation size has to be made on the 1.07 in of casing instead.
Why the 32 is an uncommon choice
Because it sits between two much more popular sizes. Buyers who want more than stock generally want a 33, and buyers who want less have no reason to leave the factory tire. 32x11.50R17 is stocked in a modest number of patterns as a result, and the 1.07 in of extra width is the main thing it offers over the size already on the vehicle.
The step people actually take
265/70R17 against 33x12.50R17 is the comparison this one usually leads to — 1.39 in rather than 0.39 in, and a much larger jump in width.