305/55R20
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 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% · Marginal fit — proceed with care
305/55R20 → 275/70R18
275/70R18
Diameter +0.2% · Good fit
305/55R20 → 285/70R18
285/70R18
Diameter −1.5% · Good fit
305/55R20 → 295/70R18
295/70R18
Diameter −3.1% · Marginal fit — proceed with care
305/55R20 → 265/60R20
265/60R20
Diameter +2.1% · Good fit
305/55R20 → 275/60R20
275/60R20
Diameter +0.7% · Good fit
305/55R20 → 275/65R20
275/65R20
Diameter −2.5% · Good fit
305/55R20 → 285/55R20
285/55R20
Diameter +2.7% · Good fit
305/55R20 → 285/60R20
285/60R20
Diameter −0.8% · Good fit
305/55R20 → 285/65R20
285/65R20
Diameter −4.0% · Marginal fit — proceed with care
305/55R20 → 295/60R20
295/60R20
Diameter −2.1% · Good fit
305/55R20 → 295/65R20
295/65R20
Diameter −5.4% · Not recommended
305/55R20 → 305/50R20
305/50R20
Diameter +3.8% · Marginal fit — proceed with care
275/60R20 → 305/55R20
275/60R20
Diameter −0.7% · Good fit
285/60R20 → 305/55R20
285/60R20
Diameter +0.8% · Good fit
265/60R20 → 305/55R20
265/60R20
Diameter −2.1% · Good fit
295/60R20 → 305/55R20
295/60R20
Diameter +2.2% · Good fit
305/50R20 → 305/55R20
305/50R20
Diameter −3.6% · Marginal fit — proceed with care
275/65R20 → 305/55R20
275/65R20
Diameter +2.6% · Good fit
285/55R20 → 305/55R20
285/55R20
Diameter −2.6% · Good fit
275/55R20 → 305/55R20
275/55R20
Diameter −3.9% · Marginal fit — proceed with care
285/65R20 → 305/55R20
285/65R20
Diameter +4.1% · Marginal fit — proceed with care
305/45R22 → 305/55R20
305/45R22
Diameter −1.2% · Good fit
285/50R22 → 305/55R20
285/50R22
Diameter +0.0% · Good fit
275/70R18 → 305/55R20
275/70R18
Diameter −0.2% · Good fit
265/55R20 → 305/55R20
265/55R20
Diameter −5.2% · Not recommended
275/50R22 → 305/55R20
275/50R22
Diameter −1.1% · Good fit
305/55R20 → 275/50R22
275/50R22
Diameter +1.2% · Good fit
305/55R20 → 285/50R22
285/50R22
Diameter −0.0% · Good fit
305/55R20 → 305/45R22
305/45R22
Diameter +1.2% · Good fit
Common questions
- What is the overall diameter of a 305/55R20 tire?
- A 305/55R20 tire is about 33.21″ (844 mm) in overall diameter, with a sidewall height of 167.8 mm and a circumference of 104.33″.
- How many revolutions per mile does a 305/55R20 tire turn?
- A 305/55R20 turns roughly 607 revolutions per mile (377 per kilometre). This is the number that determines speedometer and odometer accuracy when you change tire size.
- What do the numbers in 305/55R20 mean?
- 305 is the tread width in millimetres, 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.