205/65R16 vs 235/45R18
235/45R18 is 0.17 in (4.2 mm) shorter than 205/65R16, a −0.62% diameter difference. With the speedometer set for 205/65R16, an indicated 60 mph is 59.6 mph on 235/45R18.
Is this a safe swap?
Diameter difference −0.62%: under 1%
By overall diameter alone, 235/45R18 is a near match for 205/65R16; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.
| Measurement | 205/65R16 | 235/45R18 | Difference | % diff |
|---|---|---|---|---|
| Overall diameter | 26.49 in (672.9 mm) | 26.33 in (668.7 mm) | −0.17 in (−4.2 mm) | −0.62% |
| Sidewall height | 5.25 in (133.3 mm) | 4.16 in (105.8 mm) | −1.08 in (−27.5 mm) | −20.64% |
| Section width | 8.07 in (205.0 mm) | 9.25 in (235.0 mm) | +1.18 in (+30.0 mm) | +14.63% |
| Circumference | 83.23 in (2,114.0 mm) | 82.71 in (2,100.8 mm) | −0.52 in (−13.2 mm) | −0.62% |
| Revolutions per mile | 761 | 766 | +5 | +0.63% |
| Indicated | Actual on 205/65R16 | Actual on 235/45R18 | Difference |
|---|---|---|---|
| 30 mph | 30.0 mph | 29.8 mph | −0.2 mph |
| 60 mph | 60.0 mph | 59.6 mph | −0.4 mph |
| 75 mph | 75.0 mph | 74.5 mph | −0.5 mph |
Ride-height change: 235/45R18 lowers the vehicle by 0.08 in (2.1 mm) at the axle (half the −4.2 mm diameter difference).
235/45R18 is 0.17 in shorter than 205/65R16 and 30 mm wider, a 0.62% difference in overall diameter.
With the speedometer calibrated for 205/65R16, an indicated 60 mph is actually 59.6 mph on 235/45R18, and revolutions per mile change from 761 to 766.
235/45R18 mounts on a 18-inch wheel, a plus-2 fitment from the 16-inch wheel of 205/65R16.
Size pages
Other comparisons with 205/65R16
- 205/75R14 vs 205/65R16
- 225/70R14 vs 205/65R16
- 215/75R14 vs 205/65R16
- 27x8.50R14 vs 205/65R16
- 235/60R15 vs 205/65R16
- 205/70R15 vs 205/65R16
- 225/65R15 vs 205/65R16
- 215/70R15 vs 205/65R16
Other comparisons with 235/45R18
- 215/60R16 vs 235/45R18
- 225/60R16 vs 235/45R18
- 235/50R17 vs 235/45R18
- 215/55R17 vs 235/45R18
- 235/40R18 vs 235/45R18
- 215/45R18 vs 235/45R18
- 225/45R18 vs 235/45R18
- 295/35R18 vs 235/45R18
Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.