# 255/55R18 tire size in inches

- **Diameter:** 29.0 in
- **Width:** 10.0 in
- **Sidewall:** 5.52 in
- **Revs per mile:** 694

## Quick answer

A 255/55R18 tire is **29.0 inches** (738 mm) tall and **10.0 inches** (255 mm) wide, with a 5.52-inch sidewall, and fits a 18-inch wheel. In inch sizing that is roughly 29.0x10.0R18.

## 255/55R18 dimensions

| Measurement | Inches | Millimeters |
| --- | --- | --- |
| Overall diameter | 29.0 in | 738 mm |
| Section width | 10.0 in | 255 mm |
| Sidewall height | 5.52 in | 140.3 mm |
| Rim diameter | 18 in | 457 mm |
| Circumference | 91.2 in | 2318 mm |
| Revolutions per mile | 694 | -- |

## What does 255/55R18 mean?

| Part | Value | Meaning |
| --- | --- | --- |
| Width | 255 | The tire is 255 mm wide from sidewall to sidewall. |
| Aspect ratio | 55 | The sidewall is 55% as tall as the tire is wide (140.3 mm). |
| R | R | Radial construction (nearly every modern tire). |
| Rim | 18 | Fits a 18-inch wheel. |

The load index and speed rating that follow the size (for example "98H") are on the sidewall and in your door-jamb sticker. See the [load index chart](/tools/tire-load-index-chart) and [speed rating chart](/tools/tire-speed-rating-chart).

## What sizes can replace 255/55R18?

Sizes within 3% of the overall diameter, the usual limit for keeping the speedometer, ABS and stability control accurate. Check the width fits your wheel and fender, and match the load index.

| Size | Diameter | Difference | Speedometer at 60 mph |
| --- | --- | --- | --- |
| [255/50R19](/tools/tire-size/255-50r19) | 29.0 in | -0.0% | 60.0 mph actual |
| [235/65R17](/tools/tire-size/235-65r17) | 29.0 in | -0.1% | 60.0 mph actual |
| [235/60R18](/tools/tire-size/235-60r18) | 29.1 in | +0.2% | 60.1 mph actual |
| [235/55R19](/tools/tire-size/235-55r19) | 29.2 in | +0.5% | 60.3 mph actual |
| [275/40R20](/tools/tire-size/275-40r20) | 28.7 in | -1.3% | 59.2 mph actual |
| [225/60R18](/tools/tire-size/225-60r18) | 28.6 in | -1.4% | 59.1 mph actual |
| [245/65R17](/tools/tire-size/245-65r17) | 29.5 in | +1.7% | 61.0 mph actual |
| [225/65R17](/tools/tire-size/225-65r17) | 28.5 in | -1.8% | 58.9 mph actual |

## Frequently asked questions

### How tall is a 255/55R18 tire?

A 255/55R18 tire is 29.0 inches (738 mm) tall when new and correctly inflated. Real tires vary by a few tenths of an inch between brands and tread patterns.

### Can I put 255/55R18 tires on my car?

Only if your door-jamb placard or owner's manual lists 255/55R18, or a plus-size alternative within about 3% of the original diameter that clears the suspension. The wheel must be 18 inches in diameter and the right width for a 255 mm tire.

### How many revolutions per mile does a 255/55R18 tire make?

About 694 revolutions per mile, calculated from its 91.2-inch circumference. Manufacturers' published figures are usually slightly higher because a loaded tire squats a little.

## Other 18-inch sizes

- [225/40R18](https://diagxcar.com/tools/tire-size/225-40r18)
- [225/55R18](https://diagxcar.com/tools/tire-size/225-55r18)
- [225/60R18](https://diagxcar.com/tools/tire-size/225-60r18)
- [235/45R18](https://diagxcar.com/tools/tire-size/235-45r18)
- [235/50R18](https://diagxcar.com/tools/tire-size/235-50r18)
- [235/55R18](https://diagxcar.com/tools/tire-size/235-55r18)
- [235/60R18](https://diagxcar.com/tools/tire-size/235-60r18)
- [245/45R18](https://diagxcar.com/tools/tire-size/245-45r18)
- [245/60R18](https://diagxcar.com/tools/tire-size/245-60r18)
- [265/60R18](https://diagxcar.com/tools/tire-size/265-60r18)
- [265/65R18](https://diagxcar.com/tools/tire-size/265-65r18)
- [275/65R18](https://diagxcar.com/tools/tire-size/275-65r18)
- [275/70R18](https://diagxcar.com/tools/tire-size/275-70r18)

## Tire tools

- [Tire size calculator](https://diagxcar.com/tools/tire-size-calculator)
- [Tire size decoder](https://diagxcar.com/tools/tire-size-decoder)
- [Load index chart](https://diagxcar.com/tools/tire-load-index-chart)
- [Speed rating chart](https://diagxcar.com/tools/tire-speed-rating-chart)

## Tire care

- [How long do tires last?](https://diagxcar.com/how-long/tires)
- [How often to rotate tires](https://diagxcar.com/how-often/rotate-tires)
- [Uneven tire wear](https://diagxcar.com/symptoms/uneven-tire-wear)

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Source page: https://diagxcar.com/tools/tire-size/255-55r18
General information, not a substitute for a qualified mechanic.