255/70R17 tire size
A 255/70R17 tire is 31.1 inches (789 mm) tall and 10.0 inches (255 mm) wide, for a 17-inch wheel. Each sidewall is 7.0 inches (179 mm), 70% of the width, and the tire makes about 649 revolutions a mile.
Sources checked
| Dimension | 255/70R17 |
|---|---|
| Overall diameter | 31.06 in (789 mm) |
| Section width | 10.04 in (255 mm) |
| Sidewall height | 7.03 in (179 mm) |
| Aspect ratio | 70% |
| Rim diameter | 17 in |
| Circumference | 97.6 in (2,478 mm) |
| Revolutions per mile | 649 |
| Revolutions per km | 404 |
Compare 255/70R17 with another size
Metric, LT and flotation
At 60 mph on the speedometer you’re doing
61.1mph
+1.8% · the speedometer reads low
- Height
- +0.55 in (+14 mm)
- Width
- +0.39 in (+10 mm)
- Ground clearance
- +0.28 in (+7 mm)
- Each side, same wheel
- +0.20 in (+5 mm)
255/70R17 and 265/70R17 side by side
| Dimension | 255/70R17 | 265/70R17 | Change |
|---|---|---|---|
| Overall diameter | 31.06 in (789 mm) | 31.61 in (803 mm) | +0.55 in (+14 mm) |
| Section width | 10.04 in (255 mm) | 10.43 in (265 mm) | +0.39 in (+10 mm) |
| Sidewall height | 7.03 in (179 mm) | 7.30 in (186 mm) | +0.27 in (+7 mm) |
| Aspect ratio | 70% | 70% | |
| Rim diameter | 17 in | 17 in | |
| Circumference | 97.6 in | 99.3 in | +1.7 in |
| Revolutions per mile | 649 | 638 | −11 |
| Revolutions per km | 404 | 396 | −8 |
The working
- 255/70R17: sidewall = 255 mm × 70% = 178.5 mm = 7.03 in.
- Diameter = rim + 2 × sidewall = 17 + 2 × 7.03 = 31.06 in (789 mm).
- Circumference = π × 31.06 = 97.6 in; revolutions per mile = 63,360 ÷ 97.6 = 649.
- 265/70R17: sidewall = 265 mm × 70% = 185.5 mm = 7.30 in.
- Diameter = rim + 2 × sidewall = 17 + 2 × 7.30 = 31.61 in (803 mm).
- Circumference = π × 31.61 = 99.3 in; revolutions per mile = 63,360 ÷ 99.3 = 638.
- Speedometer. True speed = what it shows × new diameter ÷ old = 60 × 31.61 ÷ 31.06 = 61.1 mph.
- Ground clearance. Half the change in diameter: (31.61 − 31.06) ÷ 2 = +0.28 in.
Where the 255/70R17 numbers come from
The section width is 255 mm (10.04 inches), and each sidewall is 70% of it: 178.5 mm, or 7.03 inches. Two sidewalls and the 17-inch rim make 31.06 inches (789 mm).
One turn covers π × 31.06 = 97.6 inches, so the tire turns 649 times a mile and 404 times a kilometer.
What tire makers publish for 255/70R17
Inflated on the maker’s measuring rim. The percentage is the printed diameter against the 31.06 inches worked out above.
| Tire | Size as printed | Diameter | Width | Revs per mile |
|---|---|---|---|---|
| Toyo Open Country A/T III | 255/70R17 | 31.1 in (+0.1%) | 10.2 in | 668 |
| Toyo Open Country A/T III | LT255/70R17 | 31.1 in (+0.1%) | 10.2 in | 668 |
Other 17-inch sizes against 255/70R17
Each size’s height against 255/70R17, and what a speedometer set for 255/70R17 shows at 60 mph with that size on.
| Size | Diameter | Width | Height change | At 60 mph shown |
|---|---|---|---|---|
| 215/45R17 | 24.6 in | 8.5 in | −20.7% | 47.6 mph |
| 215/50R17 | 25.5 in | 8.5 in | −18.0% | 49.2 mph |
| 215/55R17 | 26.3 in | 8.5 in | −15.3% | 50.8 mph |
| 215/60R17 | 27.2 in | 8.5 in | −12.6% | 52.5 mph |
| 225/45R17 | 25.0 in | 8.9 in | −19.6% | 48.2 mph |
| 225/50R17 | 25.9 in | 8.9 in | −16.7% | 50.0 mph |
| 225/55R17 | 26.7 in | 8.9 in | −13.9% | 51.7 mph |
| 225/60R17 | 27.6 in | 8.9 in | −11.0% | 53.4 mph |
| 225/65R17 | 28.5 in | 8.9 in | −8.2% | 55.1 mph |
| 235/55R17 | 27.2 in | 9.3 in | −12.5% | 52.5 mph |
| 235/60R17 | 28.1 in | 9.3 in | −9.5% | 54.3 mph |
| 235/65R17 | 29.0 in | 9.3 in | −6.5% | 56.1 mph |
| 245/65R17 | 29.5 in | 9.6 in | −4.9% | 57.1 mph |
| 245/70R17 compared | 30.5 in | 9.6 in | −1.8% | 58.9 mph |
| 245/75R17 | 31.5 in | 9.6 in | +1.3% | 60.8 mph |
| 265/65R17 | 30.6 in | 10.4 in | −1.6% | 59.0 mph |
| 265/70R17 compared | 31.6 in | 10.4 in | +1.8% | 61.1 mph |
| 275/70R17 | 32.2 in | 10.8 in | +3.5% | 62.1 mph |
| 285/70R17 | 32.7 in | 11.2 in | +5.3% | 63.2 mph |
| 285/75R17 | 33.8 in | 11.2 in | +8.9% | 65.4 mph |
| 315/70R17 | 34.4 in | 12.4 in | +10.6% | 66.4 mph |
| 33x12.50R17 | 33.0 in | 12.5 in | +6.3% | 63.8 mph |
| 35x12.50R17 | 35.0 in | 12.5 in | +12.7% | 67.6 mph |
| 37x12.50R17 | 37.0 in | 12.5 in | +19.1% | 71.5 mph |
255/70R17 compared
Every size: the tire size calculator. With the wheels off, the nuts go back on at your vehicle’s lug nut torque.
Questions
What is 255/70R17 in inches?
About 31.1x10.0R17: 31.1 inches tall and 10.0 inches wide on a 17-inch wheel, with 7.0-inch sidewalls. Exactly, 17 + 2 × 255 mm × 0.70 ÷ 25.4 = 31.06 inches.
How many revolutions per mile does a 255/70R17 make?
649 by its diameter: 63,360 inches in a mile ÷ 97.6 inches a turn. Tire makers’ published figures are measured under load, when the tire rolls on a slightly smaller radius, and run 2.8% to 3.3% higher in Toyo’s tables.
Is LT255/70R17 the same size as P255/70R17?
In dimensions, yes: the numbers mean the same in every metric size. The letters mark what the tire is built for, and an LT tire’s load is rated differently, so check the load index and pressure your vehicle needs before swapping one for the other.
Sources
- Bridgestone Americas: Determining tire size: P-metric, Euro-metric, LT-metric, C-type and flotation sizes, and what each number means (checked October 28, 2026)
- Toyo Tires: Extensa A/S II sizes and specifications: inflated overall diameter and width, revolutions per mile (checked October 28, 2026)
- Toyo Tires: Proxes Sport A/S sizes and specifications: inflated overall diameter and width, revolutions per mile (checked October 28, 2026)
- Toyo Tires: Open Country A/T III sizes and specifications: P-metric, LT-metric and flotation sizes, with revolutions per mile (checked October 28, 2026)
- Nitto Tire: Trail Grappler M/T sizes and specs: inflated overall diameter and width, LT-metric and flotation sizes (checked October 28, 2026)
Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.