255/70R16 vs 265/70R17: wheel up, sidewall down
A Ranger's wheel-and-tire change, and a worked example of what happens when the aspect ratio is held across a wheel-size change.
265/70R17 is 1.55 in taller than 255/70R16 (5.16%) and 0.39 in wider. A speedometer calibrated for 255/70R16 would under-read by 5.16%.
Measured against each other
Overall diameter
30.06 in31.61 in+1.55 in (+5.16%)Section width
10.04 in / 255 mm10.43 in / 265 mm+0.39 in (+3.92%)Sidewall height
7.03 in7.30 in+0.28 inCircumference
94.4 in99.3 in+4.9 inRevolutions per mile
671.0638.1-32.9Ride height at the axle
——+0.78 inSpeedometer reading
——+5.16% under-read
| Dimension | 255/70R16 | 265/70R17 | Change |
|---|---|---|---|
| Overall diameter | 30.06 in | 31.61 in | +1.55 in (+5.16%) |
| Section width | 10.04 in / 255 mm | 10.43 in / 265 mm | +0.39 in (+3.92%) |
| Sidewall height | 7.03 in | 7.30 in | +0.28 in |
| Circumference | 94.4 in | 99.3 in | +4.9 in |
| Revolutions per mile | 671.0 | 638.1 | -32.9 |
| Ride height at the axle | — | — | +0.78 in |
| Speedometer reading | — | — | +5.16% under-read |
Calibrated for 255/70R16, running 265/70R17
- Dial reads 30
- 31.5 mph
- Dial reads 50
- 52.6 mph
- Dial reads 70
- 73.6 mph
- Odometer counts 100
- 105.2 mi covered
Change either size in the comparison tool, or see the full speed table in the speedometer error calculator.
Two things move here at once: the wheel grows an inch, and the tire grows 10 mm wider. Neither change is absorbed by the other, so they add.
Adding rather than cancelling
A plus-one normally drops the aspect ratio to pay for the extra wheel. This pairing keeps it at 70, so nothing is paid — the extra inch of wheel goes straight into the diameter, and the extra 10 mm of width adds its own 0.55 in on top through the aspect-ratio multiplication.
- Sidewall: 7.03 in to 7.30 in — barely changed
- Wheel: 16 in to 17 in — a full inch
- Diameter: 30.06 in to 31.61 in — 1.55 in
So about two-thirds of the height gain is the wheel and one third is the tire.
Where the ride height goes
Half of the 1.55 in ends up under the axle, as it does on any pairing. The unusual part here is what the other half sits on: a wheel an inch larger than before, so the crown of the tire has moved toward the arch while the rubber protecting the rim has barely grown at all.
Speedometer error is 5.16% — 63.1 mph at a dial reading of 60, and fifty-two extra real miles for every thousand the odometer records.
The trade the Ranger owner is making
An inch of wheel for almost no extra sidewall. The 16-inch fitment has 7.03 in of rubber between rim and road; the 17-inch fitment has 7.30 in. Anyone moving up for tire choice rather than for appearance is getting the same compliance and a larger, more expensive wheel to protect.
The two sizes also sit very differently in this catalogue. 265/70R17 is recorded as a factory fitment on ten platforms here, more than any other size; 255/70R16 is recorded on two. That is a statement about this dataset, not about what any shop has on a shelf — which is not something this site can see.
Section width, briefly
10.04 in to 10.43 in — 0.39 in, or 3.92%. A small change, and on a mid-size pickup with a relatively narrow track it is the least consequential figure on this page.
The alternative destination
Owners who want the tire without the wheel change usually look at a 33 on the original 15-inch or 16-inch wheels instead, which is a very different set of numbers.