215/40R17 vs 205/45R17
205/45R17 is a safe swap for 215/40R17 by the usual ±3% rule: the diameter differs by +2.07%.
Speedometer and odometer
With 205/45R17 on a car calibrated for 215/40R17, the speedometer reads 58.8 mph when you're really doing 60, and the odometer under-counts by 2.1%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.6 mph |
| 45 mph | 45.9 mph |
| 60 mph | 61.2 mph |
| 70 mph | 71.4 mph |
| 80 mph | 81.7 mph |
Other sizes close to 215/40R17
Questions
Can I replace 215/40R17 with 205/45R17?
205/45R17 is a safe swap for 215/40R17 by the usual ±3% rule: the diameter differs by +2.07%.
What's the difference between 215/40R17 and 205/45R17?
205/45R17 is 0.49" taller and 10 mm narrower; the sidewall is +0.25". At an indicated 60 mph you'd actually be doing 61.2 mph.
Will 205/45R17 fit on 215/40R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 205 mm tire and the fender clearance.