255/45R18
Overall diameter
27.04″
687 mm
Sidewall height
4.52″
114.8 mm
Tread width
255 mm
10.0″
Circumference
84.93″
7.1 ft
Revs per mile
746
464 per km
Wheel diameter
18″
aspect ratio 45%
Cross-section
- Overall diameter
- 27.04″
- Sidewall (each side)
- 4.52″
- Wheel
- 18″
255/45R18 compared with other sizes
All 35 practical swaps involving 255/45R18 — diameter change, speedometer impact and a fit verdict for each.
255/45R18 → 215/65R16
215/65R16
Diameter +0.1% · Good fit
255/45R18 → 225/60R16
225/60R16
Diameter +1.5% · Good fit
255/45R18 → 235/60R16
235/60R16
Diameter −0.2% · Good fit
255/45R18 → 235/55R17
235/55R17
Diameter −0.5% · Good fit
255/45R18 → 225/45R18
225/45R18
Diameter +4.1% · Marginal fit — proceed with care
255/45R18 → 235/45R18
235/45R18
Diameter +2.7% · Good fit
255/45R18 → 235/50R18
235/50R18
Diameter −0.8% · Good fit
255/45R18 → 245/40R18
245/40R18
Diameter +5.1% · Not recommended
255/45R18 → 245/45R18
245/45R18
Diameter +1.3% · Good fit
255/45R18 → 245/40R19
245/40R19
Diameter +1.2% · Good fit
255/45R18 → 255/40R19
255/40R19
Diameter +0.0% · Good fit
255/45R18 → 245/35R20
245/35R20
Diameter +1.1% · Good fit
255/45R18 → 255/35R20
255/35R20
Diameter +0.0% · Good fit
255/45R18 → 295/35R20
295/35R20
Diameter −3.9% · Marginal fit — proceed with care
255/45R18 → 225/65R16
225/65R16
Diameter −1.7% · Good fit
255/45R18 → 215/60R17
215/60R17
Diameter −0.4% · Good fit
255/45R18 → 235/55R18
235/55R18
Diameter −4.1% · Marginal fit — proceed with care
255/45R18 → 255/40R18
255/40R18
Diameter +3.9% · Marginal fit — proceed with care
235/50R18 → 255/45R18
235/50R18
Diameter +0.8% · Good fit
245/45R18 → 255/45R18
245/45R18
Diameter −1.3% · Good fit
255/40R18 → 255/45R18
255/40R18
Diameter −3.7% · Marginal fit — proceed with care
235/45R18 → 255/45R18
235/45R18
Diameter −2.6% · Good fit
255/40R19 → 255/45R18
255/40R19
Diameter −0.0% · Good fit
255/35R20 → 255/45R18
255/35R20
Diameter −0.0% · Good fit
225/45R18 → 255/45R18
225/45R18
Diameter −3.9% · Marginal fit — proceed with care
235/55R18 → 255/45R18
235/55R18
Diameter +4.2% · Marginal fit — proceed with care
245/40R18 → 255/45R18
245/40R18
Diameter −4.9% · Marginal fit — proceed with care
215/65R16 → 255/45R18
215/65R16
Diameter −0.1% · Good fit
235/60R16 → 255/45R18
235/60R16
Diameter +0.2% · Good fit
215/60R17 → 255/45R18
215/60R17
Diameter +0.5% · Good fit
235/55R17 → 255/45R18
235/55R17
Diameter +0.5% · Good fit
265/35R20 → 255/45R18
265/35R20
Diameter +1.0% · Good fit
255/45R18 → 235/45R19
235/45R19
Diameter −1.1% · Good fit
255/45R18 → 265/35R20
265/35R20
Diameter −1.0% · Good fit
255/45R18 → 275/35R20
275/35R20
Diameter −2.0% · Good fit
Common questions
- What is the overall diameter of a 255/45R18 tire?
- A 255/45R18 tire is about 27.04″ (687 mm) in overall diameter, with a sidewall height of 114.8 mm and a circumference of 84.93″.
- How many revolutions per mile does a 255/45R18 tire turn?
- A 255/45R18 turns roughly 746 revolutions per mile (464 per kilometre). This is the number that determines speedometer and odometer accuracy when you change tire size.
- What do the numbers in 255/45R18 mean?
- 255 is the tread width in millimetres, 45 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 × 45% = 114.8 mm tall.