Tire Ruler215/55R18 dimensions
| Overall diameter (height) | 27.31″ · 694 mm |
| Section width | 8.46″ · 215 mm |
| Sidewall height | 4.66″ · 118 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 6–7.5″ |
| Circumference | 85.8″ |
| Revolutions per mile | 738 |
| In inches (flotation style) | 27.3 × 8.5R18 |
How it’s calculated: the sidewall is 55% of the 215 mm width = 118.3 mm (4.66″). Add two sidewalls to the 18″ wheel: 18 + 2 × 4.66 = 27.31″.
Bigger tires than 215/55R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 225/55R18 | 27.7″ | +0.43″ (+1.6%) | 61.0 mph |
| 235/55R18 | 28.2″ | +0.87″ (+3.2%) | 61.9 mph |
| 225/60R18 | 28.6″ | +1.32″ (+4.8%) | 62.9 mph |
| 255/55R18 | 29.0″ | +1.73″ (+6.3%) | 63.8 mph |
| 235/60R18 | 29.1″ | +1.79″ (+6.6%) | 63.9 mph |
“60 mph reads” is your real speed when a speedometer set up for 215/55R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 215/55R18
Within 1.5% of the same height on an 18″ wheel. Usually interchangeable for the speedometer; check width, load index and clearance.
| Size | Height | Width | Difference |
|---|---|---|---|
| 235/50R18 | 27.3″ | 9.3″ | −0.2% |
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 225/70R15: 27.4″ tall on a 15″ wheel (+0.3%)
- 215/65R16: 27.0″ tall on a 16″ wheel (−1.1%)
- 225/60R17: 27.6″ tall on a 17″ wheel (+1.2%)
- 215/60R17: 27.2″ tall on a 17″ wheel (−0.6%)
- 235/55R17: 27.2″ tall on a 17″ wheel (−0.5%)
- 245/45R19: 27.7″ tall on a 19″ wheel (+1.4%)
- 225/45R19: 27.0″ tall on a 19″ wheel (−1.2%)
- 235/45R19: 27.3″ tall on a 19″ wheel (+0.1%)
Frequently asked questions
Is 215/55R18 a 27 inch tire?
Not quite. 215/55R18 is 27.31 inches tall, between a 27 and a 28 inch tire.
What size is 215/55R18 in inches?
215/55R18 is 27.3 inches tall (overall diameter), 8.5 inches wide, with a 4.7 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 215/55R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 235/50R18 (27.3"). Check load index and width before swapping.
What rim width fits 215/55R18?
As a rule of thumb, about 6–7.5 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 215/55R18 make?
About 738 revolutions per mile in theory (circumference 85.8 in). Real tires turn slightly more because they flatten under load.