245/45R18 tire size
A 245/45R18 tire is 26.7 inches tall and 9.6 inches wide. Here are its full dimensions, what the numbers mean, and the sizes you can swap it for.
- Overall diameter
- 26.68″ (678 mm)
- Section width
- 9.65″ (245 mm)
- Sidewall height
- 4.34″ (110 mm)
- Wheel diameter
- 18″
- Circumference
- 83.8″
- Revolutions per mile
- 756
What 245/45R18 means
- 245: the tire is 245 mm (9.6 in) wide from sidewall to sidewall.
- 45: the sidewall is 45% of the width, 110.3 mm (4.34 in) tall.
- R: radial construction, used by almost every modern tire.
- 18: it fits a 18-inch wheel.
Overall diameter = 18 + 2 × 4.34 = 26.68 inches.
Sizes equivalent to 245/45R18
These sizes are within 3% of the overall diameter, the usual limit for swapping without speedometer problems.
| Size | Diameter | Difference | Speedometer at 60 mph |
|---|---|---|---|
| 245/40R19 | 26.7″ | +0.1% | 60.1 mph actual |
| 245/35R20 | 26.8″ | +0.3% | 60.2 mph actual |
| 225/50R18 | 26.9″ | +0.7% | 60.4 mph actual |
| 235/35R20 | 26.5″ | -0.8% | 59.5 mph actual |
| 235/40R19 | 26.4″ | -1.0% | 59.4 mph actual |
| 225/45R19 | 27.0″ | +1.1% | 60.7 mph actual |
| 265/40R18 | 26.3″ | -1.3% | 59.2 mph actual |
| 255/35R20 | 27.0″ | +1.3% | 60.8 mph actual |
| 255/40R19 | 27.0″ | +1.3% | 60.8 mph actual |
| 235/45R18 | 26.3″ | -1.3% | 59.2 mph actual |
Going a size taller? 235/50R18 is 27.3″ tall, 2.1% more than 245/45R18. Compare any two sizes in the tire size calculator.
See every common size side by side in the tire size chart.
Questions
What is 245/45R18 in inches?
A 245/45R18 tire is about 26.7 inches tall (678 mm) and 9.6 inches wide, on a 18-inch wheel. In flotation sizing that's roughly 26.7x9.6R18.
How tall is a 245/45R18 tire?
The overall diameter is 26.68 inches: the 18-inch wheel plus two 4.34-inch sidewalls. Actual tires vary by a few tenths of an inch between brands and models.
How many revolutions per mile does a 245/45R18 make?
About 756 revolutions per mile, from a circumference of 83.8 inches.
