255/45R20 tire size
A 255/45R20 tire is 29.0 inches tall and 10.0 inches wide. Here are its full dimensions, what the numbers mean, and the sizes you can swap it for.
- Overall diameter
- 29.04″ (737 mm)
- Section width
- 10.04″ (255 mm)
- Sidewall height
- 4.52″ (115 mm)
- Wheel diameter
- 20″
- Circumference
- 91.2″
- Revolutions per mile
- 695
What 255/45R20 means
- 255: the tire is 255 mm (10.0 in) wide from sidewall to sidewall.
- 45: the sidewall is 45% of the width, 114.8 mm (4.52 in) tall.
- R: radial construction, used by almost every modern tire.
- 20: it fits a 20-inch wheel.
Overall diameter = 20 + 2 × 4.52 = 29.04 inches.
Sizes equivalent to 255/45R20
These sizes are within 3% of the overall diameter, the usual limit for swapping without speedometer problems.
| Size | Diameter | Difference | Speedometer at 60 mph |
|---|---|---|---|
| 255/40R21 | 29.0″ | -0.0% | 60.0 mph actual |
| 255/35R22 | 29.0″ | -0.0% | 60.0 mph actual |
| 235/50R20 | 29.3″ | +0.7% | 60.4 mph actual |
| 265/35R22 | 29.3″ | +0.9% | 60.6 mph actual |
| 245/35R22 | 28.8″ | -1.0% | 59.4 mph actual |
| 235/45R21 | 29.3″ | +1.0% | 60.6 mph actual |
| 265/40R21 | 29.3″ | +1.1% | 60.6 mph actual |
| 245/40R21 | 28.7″ | -1.1% | 59.3 mph actual |
| 245/45R20 | 28.7″ | -1.2% | 59.3 mph actual |
| 265/45R20 | 29.4″ | +1.2% | 60.7 mph actual |
Going a size taller? 265/50R20 is 30.4″ tall, 4.8% more than 255/45R20. Compare any two sizes in the tire size calculator.
See every common size side by side in the tire size chart.
Questions
What is 255/45R20 in inches?
A 255/45R20 tire is about 29.0 inches tall (737 mm) and 10.0 inches wide, on a 20-inch wheel. In flotation sizing that's roughly 29.0x10.0R20.
How tall is a 255/45R20 tire?
The overall diameter is 29.04 inches: the 20-inch wheel plus two 4.52-inch sidewalls. Actual tires vary by a few tenths of an inch between brands and models.
How many revolutions per mile does a 255/45R20 make?
About 695 revolutions per mile, from a circumference of 91.2 inches.
