235/55R18
Overall diameter
28.18″
716 mm
Sidewall height
5.09″
129.3 mm
Tread width
235 mm
9.3″
Circumference
88.52″
7.4 ft
Revs per mile
716
445 per km
Wheel diameter
18″
aspect ratio 55%
Cross-section
- Overall diameter
- 28.18″
- Sidewall (each side)
- 5.09″
- Wheel
- 18″
235/55R18 compared with other sizes
All 30 practical swaps involving 235/55R18 — diameter change, speedometer impact and a fit verdict for each.
235/55R18 → 235/50R18
235/50R18
Diameter +3.4% · Marginal fit — proceed with care
235/55R18 → 235/60R18
235/60R18
Diameter −3.2% · Marginal fit — proceed with care
235/55R18 → 255/55R18
255/55R18
Diameter −3.0% · Good fit
235/55R18 → 215/70R16
215/70R16
Diameter +1.2% · Good fit
235/55R18 → 225/70R16
225/70R16
Diameter −0.8% · Good fit
235/55R18 → 235/70R16
235/70R16
Diameter −2.7% · Good fit
235/55R18 → 215/65R17
215/65R17
Diameter +0.6% · Good fit
235/55R18 → 225/65R17
225/65R17
Diameter −1.2% · Good fit
235/55R18 → 235/60R17
235/60R17
Diameter +0.3% · Good fit
235/55R18 → 225/60R18
225/60R18
Diameter −1.6% · Good fit
225/60R18 → 235/55R18
225/60R18
Diameter +1.6% · Good fit
235/60R18 → 235/55R18
235/60R18
Diameter +3.3% · Marginal fit — proceed with care
235/50R18 → 235/55R18
235/50R18
Diameter −3.3% · Marginal fit — proceed with care
255/55R18 → 235/55R18
255/55R18
Diameter +3.1% · Marginal fit — proceed with care
235/50R19 → 235/55R18
235/50R19
Diameter +0.3% · Good fit
235/60R17 → 235/55R18
235/60R17
Diameter −0.3% · Good fit
255/45R18 → 235/55R18
255/45R18
Diameter −4.1% · Marginal fit — proceed with care
245/60R18 → 235/55R18
245/60R18
Diameter +5.0% · Marginal fit — proceed with care
245/45R18 → 235/55R18
245/45R18
Diameter −5.3% · Not recommended
255/45R19 → 235/55R18
255/45R19
Diameter −0.5% · Good fit
215/65R17 → 235/55R18
215/65R17
Diameter −0.6% · Good fit
225/70R16 → 235/55R18
225/70R16
Diameter +0.8% · Good fit
215/70R16 → 235/55R18
215/70R16
Diameter −1.2% · Good fit
225/65R17 → 235/55R18
225/65R17
Diameter +1.2% · Good fit
235/55R18 → 245/60R18
245/60R18
Diameter −4.7% · Marginal fit — proceed with care
235/55R18 → 255/45R18
255/45R18
Diameter +4.2% · Marginal fit — proceed with care
235/55R18 → 235/50R19
235/50R19
Diameter −0.3% · Good fit
235/55R18 → 255/45R19
255/45R19
Diameter +0.5% · Good fit
235/55R18 → 245/40R20
245/40R20
Diameter +1.7% · Good fit
235/55R18 → 235/45R18
235/45R18
Diameter +7.0% · Not recommended
Common questions
- What is the overall diameter of a 235/55R18 tire?
- A 235/55R18 tire is about 28.18″ (716 mm) in overall diameter, with a sidewall height of 129.3 mm and a circumference of 88.52″.
- How many revolutions per mile does a 235/55R18 tire turn?
- A 235/55R18 turns roughly 716 revolutions per mile (445 per kilometre). This is the number that determines speedometer and odometer accuracy when you change tire size.
- What do the numbers in 235/55R18 mean?
- 235 is the tread width in millimetres, 55 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 235 × 55% = 129.3 mm tall.