235/55R18 tire size
A 235/55R18 tire is 28.2 inches tall and 9.3 inches wide. Here are its full dimensions, what the numbers mean, and the sizes you can swap it for.
- Overall diameter
- 28.18″ (716 mm)
- Section width
- 9.25″ (235 mm)
- Sidewall height
- 5.09″ (129 mm)
- Wheel diameter
- 18″
- Circumference
- 88.5″
- Revolutions per mile
- 716
What 235/55R18 means
- 235: the tire is 235 mm (9.3 in) wide from sidewall to sidewall.
- 55: the sidewall is 55% of the width, 129.3 mm (5.09 in) tall.
- R: radial construction, used by almost every modern tire.
- 18: it fits a 18-inch wheel.
Overall diameter = 18 + 2 × 5.09 = 28.18 inches.
Sizes equivalent to 235/55R18
These sizes are within 3% of the overall diameter, the usual limit for swapping without speedometer problems.
| Size | Diameter | Difference | Speedometer at 60 mph |
|---|---|---|---|
| 215/60R18 | 28.2″ | -0.1% | 60.0 mph actual |
| 235/50R19 | 28.3″ | +0.3% | 60.2 mph actual |
| 215/55R19 | 28.3″ | +0.5% | 60.3 mph actual |
| 255/50R18 | 28.0″ | -0.5% | 59.7 mph actual |
| 255/45R19 | 28.0″ | -0.5% | 59.7 mph actual |
| 255/40R20 | 28.0″ | -0.5% | 59.7 mph actual |
| 235/45R20 | 28.3″ | +0.5% | 60.3 mph actual |
| 225/45R20 | 28.0″ | -0.7% | 59.6 mph actual |
| 215/50R20 | 28.5″ | +1.0% | 60.6 mph actual |
| 225/50R19 | 27.9″ | -1.1% | 59.3 mph actual |
Going a size taller? 225/60R18 is 28.6″ tall, 1.6% more than 235/55R18. Compare any two sizes in the tire size calculator.
See every common size side by side in the tire size chart.
Questions
What is 235/55R18 in inches?
A 235/55R18 tire is about 28.2 inches tall (716 mm) and 9.3 inches wide, on a 18-inch wheel. In flotation sizing that's roughly 28.2x9.3R18.
How tall is a 235/55R18 tire?
The overall diameter is 28.18 inches: the 18-inch wheel plus two 5.09-inch sidewalls. Actual tires vary by a few tenths of an inch between brands and models.
How many revolutions per mile does a 235/55R18 make?
About 716 revolutions per mile, from a circumference of 88.5 inches.
