305/55R20 tire size
305/55R20 is a metric size: 33.2" tall, 12.0" wide, on a 20" rim — about a 33x12.00R20. The sidewall is 6.6" and the tire turns 607 times per mile.
305/55R20 specs
| Overall diameter (height) | 33.21" · 844 mm |
|---|---|
| Section width | 12.01" · 305 mm |
| Sidewall height | 6.60" · 168 mm (55% of width) |
| Rim diameter | 20" |
| Circumference | 104.33" · 2.650 m |
| Revolutions per mile | 607 (377 per km) |
| Inch (flotation) equivalent | 33x12.00R20 |
Equivalent sizes on a 20" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 275/55R20 common | 31.91" | -3.91% | -30 mm | 57.7 mph | compare → |
| 275/60R20 common | 32.99" | -0.65% | -30 mm | 59.6 mph | compare → |
| 275/65R20 common | 34.07" | +2.61% | -30 mm | 61.6 mph | compare → |
| 265/60R20 common | 32.52" | -2.07% | -40 mm | 58.8 mph | compare → |
| 285/55R20 common | 32.34" | -2.61% | -20 mm | 58.4 mph | compare → |
| 285/60R20 common | 33.46" | +0.77% | -20 mm | 60.5 mph | compare → |
| 33x12.50R20 common | 33.00" | -0.63% | +13 mm | 59.6 mph | compare → |
| 295/60R20 | 33.94" | +2.19% | -10 mm | 61.3 mph | compare → |
| 295/55R20 | 32.78" | -1.30% | -10 mm | 59.2 mph | compare → |
| 285/65R20 | 34.59" | +4.15% | -20 mm | 62.5 mph | compare → |
| 245/60R20 | 31.57" | -4.92% | -60 mm | 57.0 mph | compare → |
| 305/50R20 | 32.01" | -3.62% | 0 mm | 57.8 mph | compare → |
| 255/60R20 | 32.05" | -3.50% | -50 mm | 57.9 mph | compare → |
| 33x13.50R20 | 33.00" | -0.63% | +38 mm | 59.6 mph | calculate → |
| 33x11.50R20 | 33.00" | -0.63% | -13 mm | 59.6 mph | calculate → |
| 375/45R20 | 33.29" | +0.24% | +70 mm | 60.1 mph | calculate → |
| 33x12.00R20 | 33.00" | -0.63% | 0 mm | 59.6 mph | calculate → |
| 33x22.00R20 | 33.00" | -0.63% | +254 mm | 59.6 mph | calculate → |
| 325/50R20 | 32.80" | -1.24% | +20 mm | 59.3 mph | calculate → |
| 34x11.50R20 | 34.00" | +2.38% | -13 mm | 61.4 mph | calculate → |
| 305/60R20 | 34.41" | +3.62% | 0 mm | 62.2 mph | calculate → |
| 33x14.50R20 | 33.00" | -0.63% | +63 mm | 59.6 mph | calculate → |
| 355/50R20 | 33.98" | +2.31% | +50 mm | 61.4 mph | calculate → |
| 315/50R20 | 32.40" | -2.43% | +10 mm | 58.5 mph | calculate → |
| 295/50R20 | 31.61" | -4.80% | -10 mm | 57.1 mph | calculate → |
Plus / minus sizing: 19" and 21" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 275/55R21 | 32.91" | -0.90% | -30 mm | 59.5 mph | calculate → |
Try another size against 305/55R20
Questions
What size is 305/55R20 in inches?
305/55R20 is about 33.2" tall and 12.0" wide on a 20-inch rim — roughly a 33x12.00R20 in inch sizing.
What does 305/55R20 mean?
305 mm section width, sidewall 55% of the width (6.60"), radial construction, 20-inch rim.
What tire sizes are equivalent to 305/55R20?
On the same 20" rim, within 3% of the diameter: 375/45R20 (+0.24%), 33x11.50R20 (-0.63%), 33x12.50R20 (-0.63%), 33x12.00R20 (-0.63%), 33x13.50R20 (-0.63%), 33x14.50R20 (-0.63%).
How many revolutions per mile does a 305/55R20 tire make?
About 607 revolutions per mile (circumference 104.3").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.