305/55R20
A 305/55R20 tire is 33.21 inches tall and 12.0 inches wide, with a 6.60-inch sidewall, mounted on a 20-inch wheel.
Overall diameter
33.21″
844 mm
Sidewall height
6.60″
167.8 mm
Tread width
305 mm
12.0″
Circumference
104.33″
8.7 ft
Revs per mile
607
377 per km
Wheel diameter
20″
aspect ratio 55%
Cross-section
- Overall diameter
- 33.21″
- Sidewall (each side)
- 6.60″
- Wheel
- 20″
305/55R20 in inches and millimeters
Every dimension of a 305/55R20, converted both ways. Calculated from the size code, accurate to about 1%.
| Measurement | Inches | Millimeters |
|---|---|---|
| Overall diameter (height) | 33.21″ | 844 mm |
| Tread width | 12.0″ | 305 mm |
| Sidewall height | 6.60″ | 167.8 mm |
| Wheel diameter | 20″ | 508 mm |
| Circumference | 104.33″ | 2650 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.
305/55R20 compared with other sizes
All 30 practical swaps involving 305/55R20 — diameter change, speedometer impact and a fit verdict for each.
305/55R20 → 275/55R20
275/55R20
Diameter +4.1% · Borderline. Check clearance first
305/55R20 → 275/70R18
275/70R18
Diameter +0.2% · This fits
305/55R20 → 285/70R18
285/70R18
Diameter −1.5% · This fits
305/55R20 → 295/70R18
295/70R18
Diameter −3.1% · Borderline. Check clearance first
305/55R20 → 265/60R20
265/60R20
Diameter +2.1% · This fits
305/55R20 → 275/60R20
275/60R20
Diameter +0.7% · This fits
305/55R20 → 275/65R20
275/65R20
Diameter −2.5% · This fits
305/55R20 → 285/55R20
285/55R20
Diameter +2.7% · This fits
305/55R20 → 285/60R20
285/60R20
Diameter −0.8% · This fits
305/55R20 → 285/65R20
285/65R20
Diameter −4.0% · Borderline. Check clearance first
305/55R20 → 295/60R20
295/60R20
Diameter −2.1% · This fits
305/55R20 → 295/65R20
295/65R20
Diameter −5.4% · Too big a jump
305/55R20 → 305/50R20
305/50R20
Diameter +3.8% · Borderline. Check clearance first
275/60R20 → 305/55R20
275/60R20
Diameter −0.7% · This fits
285/60R20 → 305/55R20
285/60R20
Diameter +0.8% · This fits
265/60R20 → 305/55R20
265/60R20
Diameter −2.1% · This fits
295/60R20 → 305/55R20
295/60R20
Diameter +2.2% · This fits
305/50R20 → 305/55R20
305/50R20
Diameter −3.6% · Borderline. Check clearance first
275/65R20 → 305/55R20
275/65R20
Diameter +2.6% · This fits
285/55R20 → 305/55R20
285/55R20
Diameter −2.6% · This fits
275/55R20 → 305/55R20
275/55R20
Diameter −3.9% · Borderline. Check clearance first
285/65R20 → 305/55R20
285/65R20
Diameter +4.1% · Borderline. Check clearance first
305/45R22 → 305/55R20
305/45R22
Diameter −1.2% · This fits
285/50R22 → 305/55R20
285/50R22
Diameter +0.0% · This fits
275/70R18 → 305/55R20
275/70R18
Diameter −0.2% · This fits
265/55R20 → 305/55R20
265/55R20
Diameter −5.2% · Too big a jump
275/50R22 → 305/55R20
275/50R22
Diameter −1.1% · This fits
305/55R20 → 275/50R22
275/50R22
Diameter +1.2% · This fits
305/55R20 → 285/50R22
285/50R22
Diameter −0.0% · This fits
305/55R20 → 305/45R22
305/45R22
Diameter +1.2% · This fits
Common questions
- What is 305/55R20 in inches?
- A 305/55R20 tire is 33.21 inches tall and 12.0 inches wide, with a 6.60-inch sidewall, mounted on a 20-inch wheel. In metric that is 844 mm tall and 305 mm wide. The circumference is 104.33 inches.
- How tall is a 305/55R20 tire?
- 33.21 inches, or 844 mm. That is the overall diameter, wheel included. It turns about 607 times per mile, which is what your speedometer counts.
- What do the numbers in 305/55R20 mean?
- 305 is the tread width in millimeters, 55 is the aspect ratio — the sidewall height as a percentage of the tread width — and 20 is the wheel diameter in inches. So the sidewall is 305 × 55% = 167.8 mm tall.