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305/65R20 tire size in inches
305/65R20 is 35.61" tall and 12.01" wide, and fits a 20" rim. In flotation (inch) sizing that is roughly 35.6x12.0R20.
305/65R20 dimensions
| Measurement | Inches | Metric |
|---|---|---|
| Overall diameter (height) | 35.61" | 905 mm |
| Section width | 12.01" | 305 mm |
| Sidewall height | 7.81" | 198.2 mm |
| Rim diameter | 20" | 508.0 mm |
| Circumference | 111.9" | 2841 mm |
| Revolutions per mile | 566 | |
| Aspect ratio | 65% (sidewall is 65% of the width) | |
Drawn to scale
Among the 131 sizes for 20" wheels on this site, 305/65R20 is #101 by height (shortest: 225/30R20, tallest: 365/85R20).
305/65R20 against the most popular 20" sizes
| Popular size | Height | Width | Sidewall | Speedo at true 60 |
|---|---|---|---|---|
| 275/60R20 | -2.62" (-7.36%) | -1.18" | -1.31" | 64.8 mph |
| 275/65R20 | -1.54" (-4.32%) | -1.18" | -0.77" | 62.7 mph |
| 275/55R20 | -3.70" (-10.39%) | -1.18" | -1.86" | 67 mph |
| 305/55R20 | -2.40" (-6.74%) | 0.00" | -1.21" | 64.3 mph |
| 295/65R20 | -0.51" (-1.43%) | -0.40" | -0.26" | 60.9 mph |
How the 305/65R20 numbers are worked out
The size code reads as 305 mm section width, 65% aspect ratio, R for radial construction and 20-inch wheel.
- Sidewall = 305 × 65% = 198.2 mm = 7.81"
- Diameter = 20" + 2 × 7.81" = 35.61"
- Circumference = π × 35.61" = 111.9"
- Revs per mile = 63,360" ÷ 111.9" = 566
Sizes that can replace 305/65R20 on a 20" wheel
Within 3% of 35.61". Last column: speedometer reading at a true 60 mph.
| Size | Diameter | Width | Difference | Speedo at true 60 mph |
|---|---|---|---|---|
| 265/75R20 | 35.65" | 10.43" | +0.11% | 59.9 mph |
| 285/70R20 | 35.71" | 11.22" | +0.28% | 59.8 mph |
| 280/70R20 | 35.43" | 11.02" | -0.51% | 60.3 mph |
| 335/60R20 | 35.83" | 13.19" | +0.62% | 59.6 mph |
| 355/55R20 | 35.37" | 13.98" | -0.67% | 60.4 mph |
| 325/60R20 | 35.35" | 12.80" | -0.73% | 60.4 mph |
| 275/70R20 | 35.16" | 10.83" | -1.26% | 60.8 mph |
| 320/60R20 | 35.12" | 12.60" | -1.38% | 60.8 mph |
| 295/65R20 | 35.10" | 11.61" | -1.43% | 60.9 mph |
| 315/65R20 | 36.12" | 12.40" | +1.43% | 59.2 mph |
| 255/75R20 | 35.06" | 10.04" | -1.54% | 60.9 mph |
| 275/75R20 | 36.24" | 10.83" | +1.77% | 59 mph |
One size wider or narrower
- Narrower: 295/65R20 — 11.61" wide, 35.10" tall
- Wider: 315/65R20 — 12.40" wide, 36.12" tall
Same height on a different wheel size
- 295/85R16 16" (+0.37%)
- 335/75R16 16" (+0.48%)
- 315/80R16 16" (+0.65%)
- 305/80R16 16" (-1.12%)
- 325/75R16 16" (-1.18%)
- 375/65R16 16" (-1.18%)
- 285/85R16 16" (-1.52%)
- 315/75R17 17" (-0.03%)
- 295/80R17 17" (-0.08%)
- 335/70R17 17" (-0.42%)
Questions about 305/65R20
How tall is a 305/65R20 tire in inches?
A 305/65R20 tire is 35.61 inches (905 mm) tall: the 20-inch rim plus two sidewalls of 7.81 inches each.
Is 305/65R20 a 36 inch tire?
Yes. At 35.61 inches tall it is commonly called a 36-inch tire.
How many revolutions per mile does a 305/65R20 make?
About 566 revolutions per mile, based on a calculated circumference of 111.9 inches.
What size can replace 305/65R20?
265/75R20 is the closest match on a 20" rim (+0.11% height). Check load index, speed rating and clearance first.
Compare 305/65R20 against any other size with the tire size calculator.