245/40R20
Overall diameter
27.72″
704 mm
Sidewall height
3.86″
98.0 mm
Tread width
245 mm
9.6″
Circumference
87.07″
7.3 ft
Revs per mile
728
452 per km
Wheel diameter
20″
aspect ratio 40%
Cross-section
- Overall diameter
- 27.72″
- Sidewall (each side)
- 3.86″
- Wheel
- 20″
245/40R20 compared with other sizes
All 25 practical swaps involving 245/40R20 — diameter change, speedometer impact and a fit verdict for each.
245/40R20 → 245/45R19
245/45R19
Diameter +0.1% · Good fit
245/40R20 → 275/40R19
275/40R19
Diameter +0.2% · Good fit
245/40R20 → 245/35R20
245/35R20
Diameter +3.6% · Marginal fit — proceed with care
245/40R20 → 255/35R20
255/35R20
Diameter +2.5% · Good fit
245/40R20 → 255/45R20
255/45R20
Diameter −4.5% · Marginal fit — proceed with care
245/40R20 → 255/45R19
255/45R19
Diameter −1.1% · Good fit
275/35R20 → 245/40R20
275/35R20
Diameter −0.5% · Good fit
265/35R20 → 245/40R20
265/35R20
Diameter −1.5% · Good fit
245/35R20 → 245/40R20
245/35R20
Diameter −3.5% · Marginal fit — proceed with care
245/45R20 → 245/40R20
245/45R20
Diameter +3.5% · Marginal fit — proceed with care
255/35R20 → 245/40R20
255/35R20
Diameter −2.5% · Good fit
275/40R20 → 245/40R20
275/40R20
Diameter +3.4% · Marginal fit — proceed with care
245/45R19 → 245/40R20
245/45R19
Diameter −0.1% · Good fit
255/45R20 → 245/40R20
255/45R20
Diameter +4.8% · Marginal fit — proceed with care
275/40R19 → 245/40R20
275/40R19
Diameter −0.2% · Good fit
255/45R19 → 245/40R20
255/45R19
Diameter +1.2% · Good fit
235/45R19 → 245/40R20
235/45R19
Diameter −1.4% · Good fit
235/55R18 → 245/40R20
235/55R18
Diameter +1.7% · Good fit
235/50R18 → 245/40R20
235/50R18
Diameter −1.7% · Good fit
235/50R19 → 245/40R20
235/50R19
Diameter +1.9% · Good fit
245/40R20 → 245/45R20
245/45R20
Diameter −3.4% · Marginal fit — proceed with care
245/40R20 → 265/35R20
265/35R20
Diameter +1.5% · Good fit
245/40R20 → 275/35R20
275/35R20
Diameter +0.5% · Good fit
245/40R20 → 275/40R20
275/40R20
Diameter −3.3% · Marginal fit — proceed with care
245/40R20 → 275/55R20
275/55R20
Diameter −13.1% · Not recommended
Common questions
- What is the overall diameter of a 245/40R20 tire?
- A 245/40R20 tire is about 27.72″ (704 mm) in overall diameter, with a sidewall height of 98.0 mm and a circumference of 87.07″.
- How many revolutions per mile does a 245/40R20 tire turn?
- A 245/40R20 turns roughly 728 revolutions per mile (452 per kilometre). This is the number that determines speedometer and odometer accuracy when you change tire size.
- What do the numbers in 245/40R20 mean?
- 245 is the tread width in millimetres, 40 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 245 × 40% = 98.0 mm tall.