255/70R18
Overall diameter
32.06″
814 mm
Sidewall height
7.03″
178.5 mm
Tread width
255 mm
10.0″
Circumference
100.70″
8.4 ft
Revs per mile
629
391 per km
Wheel diameter
18″
aspect ratio 70%
Cross-section
- Overall diameter
- 32.06″
- Sidewall (each side)
- 7.03″
- Wheel
- 18″
255/70R18 compared with other sizes
All 31 practical swaps involving 255/70R18 — diameter change, speedometer impact and a fit verdict for each.
255/70R18 → 275/55R20
275/55R20
Diameter +0.5% · Good fit
255/70R18 → 265/75R16
265/75R16
Diameter +1.3% · Good fit
255/70R18 → 285/75R16
285/75R16
Diameter −2.4% · Good fit
255/70R18 → 235/80R17
235/80R17
Diameter +0.8% · Good fit
255/70R18 → 255/75R17
255/75R17
Diameter −0.0% · Good fit
255/70R18 → 275/70R17
275/70R17
Diameter −0.3% · Good fit
255/70R18 → 245/65R18
245/65R18
Diameter +5.0% · Marginal fit — proceed with care
255/70R18 → 255/65R18
255/65R18
Diameter +3.2% · Marginal fit — proceed with care
275/65R18 → 255/70R18
275/65R18
Diameter +0.1% · Good fit
265/65R18 → 255/70R18
265/65R18
Diameter −1.5% · Good fit
285/65R18 → 255/70R18
285/65R18
Diameter +1.7% · Good fit
265/70R18 → 255/70R18
265/70R18
Diameter +1.7% · Good fit
285/60R18 → 255/70R18
285/60R18
Diameter −1.8% · Good fit
255/65R18 → 255/70R18
255/65R18
Diameter −3.1% · Marginal fit — proceed with care
275/60R18 → 255/70R18
275/60R18
Diameter −3.3% · Marginal fit — proceed with care
275/70R18 → 255/70R18
275/70R18
Diameter +3.4% · Marginal fit — proceed with care
255/75R17 → 255/70R18
255/75R17
Diameter +0.0% · Good fit
245/65R18 → 255/70R18
245/65R18
Diameter −4.7% · Marginal fit — proceed with care
265/60R18 → 255/70R18
265/60R18
Diameter −4.8% · Marginal fit — proceed with care
285/70R18 → 255/70R18
285/70R18
Diameter +5.2% · Not recommended
275/70R17 → 255/70R18
275/70R17
Diameter +0.3% · Good fit
275/55R20 → 255/70R18
275/55R20
Diameter −0.5% · Good fit
255/70R18 → 265/65R18
265/65R18
Diameter +1.6% · Good fit
255/70R18 → 265/70R18
265/70R18
Diameter −1.7% · Good fit
255/70R18 → 275/60R18
275/60R18
Diameter +3.4% · Marginal fit — proceed with care
255/70R18 → 275/65R18
275/65R18
Diameter −0.1% · Good fit
255/70R18 → 275/70R18
275/70R18
Diameter −3.3% · Marginal fit — proceed with care
255/70R18 → 285/60R18
285/60R18
Diameter +1.9% · Good fit
255/70R18 → 285/65R18
285/65R18
Diameter −1.6% · Good fit
255/70R18 → 285/70R18
285/70R18
Diameter −4.9% · Marginal fit — proceed with care
255/70R18 → 235/45R18
235/45R18
Diameter +21.8% · Not recommended
Common questions
- What is the overall diameter of a 255/70R18 tire?
- A 255/70R18 tire is about 32.06″ (814 mm) in overall diameter, with a sidewall height of 178.5 mm and a circumference of 100.70″.
- How many revolutions per mile does a 255/70R18 tire turn?
- A 255/70R18 turns roughly 629 revolutions per mile (391 per kilometre). This is the number that determines speedometer and odometer accuracy when you change tire size.
- What do the numbers in 255/70R18 mean?
- 255 is the tread width in millimetres, 70 is the aspect ratio — the sidewall height as a percentage of the tread width — and 18 is the wheel diameter in inches. So the sidewall is 255 × 70% = 178.5 mm tall.