205/65R15 vs 215/50R17
New overall diameter
25.46″
was 25.49″
True speed at an indicated 60
59.9 mph
speedometer reads high
Revolutions per mile
792
was 791 · +1
Switching from 205/65R15 to 215/50R17? Everything that changes is below — sidewall, tread width, circumference, revolutions per mile and speedometer error at road speeds.
| Measurement | 205/65R15 | 215/50R17 | Change |
|---|---|---|---|
| Overall diameter | 25.49″ | 25.46″ | −0.03″ (−0.1%) |
| Sidewall height | 5.25″ (133.3 mm) | 4.23″ (107.5 mm) | −25.8 mm |
| Tread width | 205 mm | 215 mm | +10 mm |
| Circumference | 80.09″ | 80.00″ | −0.09″ |
| Revs per mile | 791 | 792 | +1 |
| Speedometer error | baseline | −0.1% | reads high |
Diameter overlay
205/65R15 215/50R17
Speedometer check
With 215/50R17 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
25.0 mph actual
35 mph shown
35.0 mph actual
45 mph shown
45.0 mph actual
55 mph shown
54.9 mph actual
65 mph shown
64.9 mph actual
75 mph shown
74.9 mph actual
Common questions
- Will 215/50R17 fit instead of 205/65R15?
- Good fit. Within the 3% rule — overall diameter changes only 0.1%. Speedometer calibration, ABS, traction control and gearing all stay in their intended range. Your speedometer will read higher than your true speed. Overall diameter goes from 25.49″ to 25.46″, a change of −0.1%. As a rule of thumb, under 3% is safe, 3–5% needs a clearance check, and over 5% is not recommended.
- How far off will my speedometer read on 215/50R17?
- At an indicated 60 mph you would actually be travelling about 59.9 mph — a −0.1% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 205/65R15 and 215/50R17?
- 205/65R15 turns roughly 791 revolutions per mile; 215/50R17 turns roughly 792. That is a change of +1 revolutions per mile, which is what shifts odometer and speedometer readings.