245/50R20 tire size
A 245/50R20 tire is 29.6 inches (753 mm) tall and 9.6 inches (245 mm) wide, for a 20-inch wheel. Each sidewall is 4.8 inches (123 mm), 50% of the width, and the tire makes about 680 revolutions a mile.
Sources checked
| Dimension | 245/50R20 |
|---|---|
| Overall diameter | 29.65 in (753 mm) |
| Section width | 9.65 in (245 mm) |
| Sidewall height | 4.82 in (123 mm) |
| Aspect ratio | 50% |
| Rim diameter | 20 in |
| Circumference | 93.1 in (2,366 mm) |
| Revolutions per mile | 680 |
| Revolutions per km | 423 |
Compare 245/50R20 with another size
Metric, LT and flotation
At 60 mph on the speedometer you’re doing
60.8mph
+1.3% · the speedometer reads low
- Height
- +0.39 in (+10 mm)
- Width
- +0.39 in (+10 mm)
- Ground clearance
- +0.20 in (+5 mm)
- Each side, same wheel
- +0.20 in (+5 mm)
245/50R20 and 255/50R20 side by side
| Dimension | 245/50R20 | 255/50R20 | Change |
|---|---|---|---|
| Overall diameter | 29.65 in (753 mm) | 30.04 in (763 mm) | +0.39 in (+10 mm) |
| Section width | 9.65 in (245 mm) | 10.04 in (255 mm) | +0.39 in (+10 mm) |
| Sidewall height | 4.82 in (123 mm) | 5.02 in (127 mm) | +0.20 in (+4 mm) |
| Aspect ratio | 50% | 50% | |
| Rim diameter | 20 in | 20 in | |
| Circumference | 93.1 in | 94.4 in | +1.3 in |
| Revolutions per mile | 680 | 671 | −9 |
| Revolutions per km | 423 | 417 | −6 |
The working
- 245/50R20: sidewall = 245 mm × 50% = 122.5 mm = 4.82 in.
- Diameter = rim + 2 × sidewall = 20 + 2 × 4.82 = 29.65 in (753 mm).
- Circumference = π × 29.65 = 93.1 in; revolutions per mile = 63,360 ÷ 93.1 = 680.
- 255/50R20: sidewall = 255 mm × 50% = 127.5 mm = 5.02 in.
- Diameter = rim + 2 × sidewall = 20 + 2 × 5.02 = 30.04 in (763 mm).
- Circumference = π × 30.04 = 94.4 in; revolutions per mile = 63,360 ÷ 94.4 = 671.
- Speedometer. True speed = what it shows × new diameter ÷ old = 60 × 30.04 ÷ 29.65 = 60.8 mph.
- Ground clearance. Half the change in diameter: (30.04 − 29.65) ÷ 2 = +0.20 in.
Where the 245/50R20 numbers come from
The section width is 245 mm (9.65 inches), and each sidewall is 50% of it: 122.5 mm, or 4.82 inches. Two sidewalls and the 20-inch rim make 29.65 inches (753 mm).
One turn covers π × 29.65 = 93.1 inches, so the tire turns 680 times a mile and 423 times a kilometer.
What tire makers publish for 245/50R20
Inflated on the maker’s measuring rim. The percentage is the printed diameter against the 29.65 inches worked out above.
| Tire | Size as printed | Diameter | Width | Revs per mile |
|---|---|---|---|---|
| Toyo Open Country A/T III | 245/50R20 | 29.7 in (+0.2%) | 10 in | 700 |
Other 20-inch sizes against 245/50R20
Each size’s height against 245/50R20, and what a speedometer set for 245/50R20 shows at 60 mph with that size on.
| Size | Diameter | Width | Height change | At 60 mph shown |
|---|---|---|---|---|
| 255/50R20 compared | 30.0 in | 10.0 in | +1.3% | 60.8 mph |
| 255/55R20 | 31.0 in | 10.0 in | +4.7% | 62.8 mph |
| 275/55R20 | 31.9 in | 10.8 in | +7.6% | 64.6 mph |
| 275/60R20 | 33.0 in | 10.8 in | +11.3% | 66.8 mph |
| 275/65R20 | 34.1 in | 10.8 in | +14.9% | 69.0 mph |
| 285/55R20 | 32.3 in | 11.2 in | +9.1% | 65.5 mph |
| 285/60R20 | 33.5 in | 11.2 in | +12.9% | 67.7 mph |
| 33x12.50R20 | 33.0 in | 12.5 in | +11.3% | 66.8 mph |
| 35x12.50R20 | 35.0 in | 12.5 in | +18.1% | 70.8 mph |
245/50R20 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 245/50R20 in inches?
About 29.6x9.6R20: 29.6 inches tall and 9.6 inches wide on a 20-inch wheel, with 4.8-inch sidewalls. Exactly, 20 + 2 × 245 mm × 0.50 ÷ 25.4 = 29.65 inches.
How many revolutions per mile does a 245/50R20 make?
680 by its diameter: 63,360 inches in a mile ÷ 93.1 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 LT245/50R20 the same size as P245/50R20?
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.