Home › 20" tire sizes › 305/55R20
305/55R20 tire size in inches
305/55R20 is 33.21" tall and 12.01" wide, and fits a 20" rim. In flotation (inch) sizing that is roughly 33.2x12.0R20.
305/55R20 dimensions
| Measurement | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 33.21" | 844 mm |
| Section width | 12.01" | 305 mm |
| Sidewall height | 6.60" | 167.8 mm |
| Rim diameter | 20" | 508.0 mm |
| Circumference | 104.3" | 2650 mm |
| Revolutions per mile | 607 | |
| Aspect ratio | 55% (sidewall is 55% of the width) | |
Drawn to scale
Among the 131 sizes for 20" wheels on this site, 305/55R20 is #74 by height (shortest: 225/30R20, tallest: 365/85R20).
What people compare 305/55R20 with
Real comparisons drivers search for, worked out against 305/55R20:
| Compared size | Height | Width | Sidewall | Speedo at true 60 |
|---|---|---|---|---|
| 275/60R20 | -0.22" (-0.66%) | -1.18" | -0.10" | 60.4 mph |
| 275/65R20 | +0.86" (+2.59%) | -1.18" | +0.44" | 58.5 mph |
| 295/60R20 | +0.73" (+2.2%) | -0.40" | +0.37" | 58.7 mph |
| 305/50R20 | -1.20" (-3.61%) | 0.00" | -0.60" | 62.2 mph |
| 275/55R20 | -1.30" (-3.91%) | -1.18" | -0.65" | 62.4 mph |
| 285/60R20 | +0.25" (+0.75%) | -0.79" | +0.13" | 59.6 mph |
| 295/55R20 | -0.43" (-1.29%) | -0.40" | -0.21" | 60.8 mph |
| 285/55R20 | -0.87" (-2.62%) | -0.79" | -0.43" | 61.6 mph |
How the 305/55R20 numbers are worked out
The size code reads as 305 mm section width, 55% aspect ratio, R for radial construction and 20-inch wheel.
- Sidewall = 305 × 55% = 167.8 mm = 6.60"
- Diameter = 20" + 2 × 6.60" = 33.21"
- Circumference = π × 33.21" = 104.3"
- Revs per mile = 63,360" ÷ 104.3" = 607
Sizes that can replace 305/55R20 on a 20" wheel
Within 3% of 33.21". Last column: speedometer reading at a true 60 mph.
| Size | Diameter | Width | Difference | Speedo at true 60 mph |
|---|---|---|---|---|
| 280/60R20 | 33.23" | 11.02" | +0.06% | 60 mph |
| 375/45R20 | 33.29" | 14.76" | +0.24% | 59.9 mph |
| 255/65R20 | 33.05" | 10.04" | -0.48% | 60.3 mph |
| 275/60R20 | 32.99" | 10.83" | -0.66% | 60.4 mph |
| 285/60R20 | 33.46" | 11.22" | +0.75% | 59.6 mph |
| 265/65R20 | 33.56" | 10.43" | +1.05% | 59.4 mph |
| 325/50R20 | 32.80" | 12.80" | -1.23% | 60.8 mph |
| 295/55R20 | 32.78" | 11.61" | -1.29% | 60.8 mph |
| 315/55R20 | 33.64" | 12.40" | +1.29% | 59.2 mph |
| 270/60R20 | 32.76" | 10.63" | -1.36% | 60.8 mph |
| 290/60R20 | 33.70" | 11.42" | +1.48% | 59.1 mph |
| 270/65R20 | 33.82" | 10.63" | +1.84% | 58.9 mph |
One size wider or narrower
- Narrower: 295/55R20 — 11.61" wide, 32.78" tall
- Wider: 315/55R20 — 12.40" wide, 33.64" tall
Same height on a different wheel size
- 305/75R15 15" (-0.6%)
- 315/75R15 15" (+1.17%)
- 265/85R15 15" (-1.42%)
- 275/80R16 16" (+0.33%)
- 255/85R16 16" (-0.42%)
- 315/70R16 16" (+0.45%)
- 295/75R16 16" (+0.63%)
- 285/75R16 16" (-1.14%)
- 305/70R16 16" (-1.2%)
- 265/80R16 16" (-1.57%)
Questions about 305/55R20
How tall is a 305/55R20 tire in inches?
A 305/55R20 tire is 33.21 inches (844 mm) tall: the 20-inch rim plus two sidewalls of 6.60 inches each.
Is 305/55R20 a 33 inch tire?
Yes. At 33.21 inches tall it is commonly called a 33-inch tire.
How many revolutions per mile does a 305/55R20 make?
About 607 revolutions per mile, based on a calculated circumference of 104.3 inches.
What size can replace 305/55R20?
280/60R20 is the closest match on a 20" rim (+0.06% height). Check load index, speed rating and clearance first.
Compare 305/55R20 against any other size with the tire size calculator.