285/70R17 vs 33x12.50R17 tire size
A 33x12.50R17 is 0.29 inches (7 mm) taller and 1.28 inches (32 mm) wider than a 285/70R17. Fit them in place of 285/70R17 tires and the speedometer reads low: at 60 mph on it you’re doing 60.5 mph, 0.9% faster, and the vehicle sits 0.15 inches (4 mm) higher.
Sources checked
| Dimension | 285/70R17 | 33x12.50R17 | Change |
|---|---|---|---|
| Overall diameter | 32.71 in (831 mm) | 33.00 in (838 mm) | +0.29 in (+7 mm) |
| Section width | 11.22 in (285 mm) | 12.50 in (318 mm) | +1.28 in (+33 mm) |
| Sidewall height | 7.85 in (200 mm) | 8.00 in (203 mm) | +0.15 in (+3 mm) |
| Aspect ratio | 70% | 64% | |
| Rim diameter | 17 in | 17 in | |
| Circumference | 102.8 in (2,610 mm) | 103.7 in (2,633 mm) | +0.9 in |
| Revolutions per mile | 617 | 611 | −6 |
| Revolutions per km | 383 | 380 | −3 |
Check another speed or size
Metric, LT and flotation
At 60 mph on the speedometer you’re doing
60.5mph
+0.9% · the speedometer reads low
- Height
- +0.29 in (+7 mm)
- Width
- +1.28 in (+32 mm)
- Ground clearance
- +0.15 in (+4 mm)
- Each side, same wheel
- +0.64 in (+16 mm)
285/70R17 and 33x12.50R17LT side by side
| Dimension | 285/70R17 | 33x12.50R17LT | Change |
|---|---|---|---|
| Overall diameter | 32.71 in (831 mm) | 33.00 in (838 mm) | +0.29 in (+7 mm) |
| Section width | 11.22 in (285 mm) | 12.50 in (318 mm) | +1.28 in (+33 mm) |
| Sidewall height | 7.85 in (200 mm) | 8.00 in (203 mm) | +0.15 in (+3 mm) |
| Aspect ratio | 70% | 64% | |
| Rim diameter | 17 in | 17 in | |
| Circumference | 102.8 in | 103.7 in | +0.9 in |
| Revolutions per mile | 617 | 611 | −6 |
| Revolutions per km | 383 | 380 | −3 |
The working
- 285/70R17: sidewall = 285 mm × 70% = 199.5 mm = 7.85 in.
- Diameter = rim + 2 × sidewall = 17 + 2 × 7.85 = 32.71 in (831 mm).
- Circumference = π × 32.71 = 102.8 in; revolutions per mile = 63,360 ÷ 102.8 = 617.
- 33x12.50R17LT: 33.00 in tall and 12.50 in wide, as the size says.
- Sidewall = (diameter − rim) ÷ 2 = (33 − 17) ÷ 2 = 8.00 in.
- Circumference = π × 33.00 = 103.7 in; revolutions per mile = 63,360 ÷ 103.7 = 611.
- Speedometer. True speed = what it shows × new diameter ÷ old = 60 × 33.00 ÷ 32.71 = 60.5 mph.
- Ground clearance. Half the change in diameter: (33.00 − 32.71) ÷ 2 = +0.15 in.
Speedometer
A 33x12.50R17 turns 611 times a mile against the 285/70R17’s 617. With a speedometer set for 285/70R17, true speed is what it shows × 33.00 ÷ 32.71:
| Speedometer shows | True speed | Difference |
|---|---|---|
| 25 mph | 25.2 mph | +0.2 mph |
| 35 mph | 35.3 mph | +0.3 mph |
| 45 mph | 45.4 mph | +0.4 mph |
| 55 mph | 55.5 mph | +0.5 mph |
| 65 mph | 65.6 mph | +0.6 mph |
| 75 mph | 75.7 mph | +0.7 mph |
Clearance
- Ground clearance: +0.15 in (+4 mm), half the change in diameter.
- Top of the tread: +0.15 in (+4 mm), so that much less room under the fender.
- Each side, on the same wheel: +0.64 in (+16 mm), toward the suspension inside and toward the fender lip outside.
A new wheel with a different width or offset moves the tire again. The sidewall goes from 7.85 to 8.00 inches.
What tire makers publish
Inflated on the maker’s measuring rim; the percentage is against the arithmetic.
| Tire | Size as printed | Diameter | Width | Revs per mile |
|---|---|---|---|---|
| Toyo Open Country A/T III | P285/70R17 | 32.8 in (+0.3%) | 11.5 in | 634 |
| Toyo Open Country A/T III, black sidewall | LT285/70R17 | 32.8 in (+0.3%) | 11.5 in | 634 |
| Toyo Open Country A/T III, outlined white letters | LT285/70R17 | 33 in (+0.9%) | 11.5 in | 630 |
| Nitto Trail Grappler M/T, load range C | LT285/70R17 | 32.99 in (+0.9%) | 11.5 in | – |
| Nitto Trail Grappler M/T, load range E | LT285/70R17 | 33.15 in (+1.3%) | 11.81 in | – |
| Toyo Open Country A/T III | 33X12.50R17LT | 32.5 in (−1.5%) | 12.5 in | 639 |
| Nitto Trail Grappler M/T | 33x12.50R17LT | 32.76 in (−0.7%) | 12.52 in | – |
Each size on its own
- 285/70R17 tire size: 32.7 × 11.2 in
- 33x12.50R17 tire size: 33.0 × 12.5 in
Other comparisons
Questions
Can I fit 33x12.50R17 tires instead of 285/70R17?
They fit the same 17-inch wheels. A 33x12.50R17 is 0.29 inches (7 mm) taller and 1.28 inches (32 mm) wider than a 285/70R17, so check three things first: that your wheels are within the 33x12.50R17’s approved rim width range, which tire makers list for each size; that it clears the fenders and suspension at full lock and full travel; and that its load index meets what your door-jamb placard asks for.
How far off is the speedometer with 33x12.50R17 tires?
With a speedometer set for 285/70R17, the speedometer reads low: at 60 mph on it you’re doing 60.5 mph, 0.9% faster. The odometer is off the same way: over 1,000 miles driven it shows 991.2.
Does 33x12.50R17 change the ground clearance?
By +0.15 inches (+4 mm), half the change in diameter, at the axles and at the lowest point under them. On the same wheel, each sidewall sits 0.64 inches further out, inside and outside.
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.