255/55R18
A 255/55R18 tire is 29.04 inches tall and 10.0 inches wide, with a 5.52-inch sidewall, mounted on a 18-inch wheel.
Common fitments: Pilot, Explorer, Durango
Overall diameter
29.04″
738 mm
Sidewall height
5.52″
140.3 mm
Tread width
255 mm
10.0″
Circumference
91.24″
7.6 ft
Revs per mile
694
431 per km
Wheel diameter
18″
aspect ratio 55%
Cross-section
- Overall diameter
- 29.04″
- Sidewall (each side)
- 5.52″
- Wheel
- 18″
255/55R18 in inches and millimeters
Every dimension of a 255/55R18, converted both ways. Calculated from the size code, accurate to about 1%.
| Measurement | Inches | Millimeters |
|---|---|---|
| Overall diameter (height) | 29.04″ | 738 mm |
| Tread width | 10.0″ | 255 mm |
| Sidewall height | 5.52″ | 140.3 mm |
| Wheel diameter | 18″ | 457 mm |
| Circumference | 91.24″ | 2318 mm |
Nominal dimensions from the size code. A real tire varies by a few millimeters between manufacturers, and a loaded tire sits slightly shorter than its free diameter.
255/55R18 compared with other sizes
All 33 practical swaps involving 255/55R18 — diameter change, speedometer impact and a fit verdict for each.
255/55R18 → 235/60R18
235/60R18
Diameter −0.2% · This fits
235/60R18 → 255/55R18
235/60R18
Diameter +0.2% · This fits
225/60R18 → 255/55R18
225/60R18
Diameter −1.4% · This fits
245/60R18 → 255/55R18
245/60R18
Diameter +1.8% · This fits
255/60R18 → 255/55R18
255/60R18
Diameter +3.5% · Borderline. Check clearance first
235/55R18 → 255/55R18
235/55R18
Diameter −3.0% · This fits
235/65R18 → 255/55R18
235/65R18
Diameter +3.4% · Borderline. Check clearance first
255/50R19 → 255/55R18
255/50R19
Diameter −0.0% · This fits
255/45R20 → 255/55R18
255/45R20
Diameter −0.0% · This fits
235/65R17 → 255/55R18
235/65R17
Diameter −0.1% · This fits
265/60R18 → 255/55R18
265/60R18
Diameter +5.1% · Too big a jump
245/65R18 → 255/55R18
245/65R18
Diameter +5.2% · Too big a jump
235/70R16 → 255/55R18
235/70R16
Diameter −0.3% · This fits
235/55R19 → 255/55R18
235/55R19
Diameter +0.5% · This fits
225/75R16 → 255/55R18
225/75R16
Diameter +0.8% · This fits
255/55R18 → 265/60R18
265/60R18
Diameter −4.8% · Borderline. Check clearance first
255/55R18 → 255/45R20
255/45R20
Diameter +0.0% · This fits
255/55R18 → 295/35R20
295/35R20
Diameter +3.2% · Borderline. Check clearance first
255/55R18 → 225/75R16
225/75R16
Diameter −0.8% · This fits
255/55R18 → 235/70R16
235/70R16
Diameter +0.3% · This fits
255/55R18 → 245/70R16
245/70R16
Diameter −1.6% · This fits
255/55R18 → 235/65R17
235/65R17
Diameter +0.1% · This fits
255/55R18 → 225/60R18
225/60R18
Diameter +1.4% · This fits
255/55R18 → 235/55R18
235/55R18
Diameter +3.1% · Borderline. Check clearance first
255/55R18 → 235/65R18
235/65R18
Diameter −3.3% · Borderline. Check clearance first
255/55R18 → 245/60R18
245/60R18
Diameter −1.8% · This fits
255/55R18 → 245/65R18
245/65R18
Diameter −4.9% · Borderline. Check clearance first
255/55R18 → 255/60R18
255/60R18
Diameter −3.3% · Borderline. Check clearance first
255/55R18 → 235/55R19
235/55R19
Diameter −0.5% · This fits
255/55R18 → 255/50R19
255/50R19
Diameter +0.0% · This fits
255/55R18 → 245/45R20
245/45R20
Diameter +1.3% · This fits
255/55R18 → 275/40R20
275/40R20
Diameter +1.3% · This fits
255/55R18 → 235/45R18
235/45R18
Diameter +10.3% · Too big a jump
Common questions
- What is 255/55R18 in inches?
- A 255/55R18 tire is 29.04 inches tall and 10.0 inches wide, with a 5.52-inch sidewall, mounted on a 18-inch wheel. In metric that is 738 mm tall and 255 mm wide. The circumference is 91.24 inches.
- How tall is a 255/55R18 tire?
- 29.04 inches, or 738 mm. That is the overall diameter, wheel included. It turns about 694 times per mile, which is what your speedometer counts.
- What do the numbers in 255/55R18 mean?
- 255 is the tread width in millimeters, 55 is the aspect ratio — the sidewall height as a percentage of the tread width — and 18 is the wheel diameter in inches. So the sidewall is 255 × 55% = 140.3 mm tall.