265/70R17 vs 33x12.50R17 — factory tire, an advertised 33
A 4Runner's factory size against the way the upgrade is actually advertised, in the notation the tire is sold under.
33x12.50R17 is 1.39 in taller than 265/70R17 (4.41%) and 2.07 in wider. A speedometer calibrated for 265/70R17 would under-read by 4.41%.
Measured against each other
Overall diameter
31.61 in33.00 in+1.39 in (+4.41%)Section width
10.43 in / 265 mm12.50 in / 318 mm+2.07 in (+19.81%)Sidewall height
7.30 in8.00 in+0.70 inCircumference
99.3 in103.7 in+4.4 inRevolutions per mile
638.1611.2-26.9Ride height at the axle
——+0.70 inSpeedometer reading
——+4.41% under-read
| Dimension | 265/70R17 | 33x12.50R17 | Change |
|---|---|---|---|
| Overall diameter | 31.61 in | 33.00 in | +1.39 in (+4.41%) |
| Section width | 10.43 in / 265 mm | 12.50 in / 318 mm | +2.07 in (+19.81%) |
| Sidewall height | 7.30 in | 8.00 in | +0.70 in |
| Circumference | 99.3 in | 103.7 in | +4.4 in |
| Revolutions per mile | 638.1 | 611.2 | -26.9 |
| Ride height at the axle | — | — | +0.70 in |
| Speedometer reading | — | — | +4.41% under-read |
Calibrated for 265/70R17, running 33x12.50R17
- Dial reads 30
- 31.3 mph
- Dial reads 50
- 52.2 mph
- Dial reads 70
- 73.1 mph
- Odometer counts 100
- 104.4 mi covered
Change either size in the comparison tool, or see the full speed table in the speedometer error calculator.
The step itself is modest. What is not modest is the two inches of extra casing that arrive with it.
Height and width are not proportional here
Diameter rises 4.41%. Section width rises 19.81%. The tire gets a little taller and a great deal wider, which is the standard shape of a metric-to-flotation move and the standard source of surprise.
In inches: 1.39 in of height, 2.07 in of width. The width change is half again as large as the height change even in absolute terms, before the percentages are considered.
Why the tire is advertised this way
Because the aftermarket sells diameters. A retailer listing "33s" for a 4Runner is listing 33x12.50R17, and the equivalent metric sizes are shelved elsewhere and described differently. An owner who thinks in terms of "going to 33s" will meet this pairing rather than a metric one, even though metric alternatives at similar heights exist.
The consequences of 4.41%
A 3.73:1 axle converts to 3.89:1, and 3.91:1 is on the shelf. Four and a half per cent is well short of what would prompt most owners to open a differential, and the conversion is here as a reference point rather than as a course of action.
Uncorrected, the same figure is a shade over three miles an hour missing at an indicated 70.
The shapes
The metric tire states a 70-series profile and has a 7.30 in sidewall. The flotation tire prints no profile at all and works out to a 64-series with an 8.00 in sidewall. Seven tenths of an inch more sidewall on a casing two inches wider — a much squatter object, which is why it looks so different in the arch despite the modest height gain.
What a 4Runner has to find room for
Two inches of casing, at full lock, with the factory wheel's offset unchanged. The height is the easy part on this platform; the width is what meets the liner and the lower control arm. Anyone reasoning from the 4.41% figure alone is reasoning from the smaller of the two numbers.
The same step in metric
265/70R17 against 285/70R17 reaches 32.71 in — a third of an inch short of the flotation 33 — while adding only 0.79 in of casing rather than 2.07 in. For anyone constrained laterally, that comparison answers a different and often more useful question.