205/50R17 vs 215/55R17
New overall diameter
26.31″
was 25.07″
True speed at an indicated 60
63.0 mph
speedometer reads low
Revolutions per mile
767
was 804 · −38
Switching from 205/50R17 to 215/55R17? Everything that changes is below — sidewall, tread width, circumference, revolutions per mile and speedometer error at road speeds.
| Measurement | 205/50R17 | 215/55R17 | Change |
|---|---|---|---|
| Overall diameter | 25.07″ | 26.31″ | +1.24″ (+4.9%) |
| Sidewall height | 4.04″ (102.5 mm) | 4.66″ (118.3 mm) | +15.8 mm |
| Tread width | 205 mm | 215 mm | +10 mm |
| Circumference | 78.76″ | 82.66″ | +3.90″ |
| Revs per mile | 804 | 767 | −38 |
| Speedometer error | baseline | +4.9% | reads low |
Diameter overlay
205/50R17 215/55R17
Speedometer check
With 215/55R17 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
26.2 mph actual
35 mph shown
36.7 mph actual
45 mph shown
47.2 mph actual
55 mph shown
57.7 mph actual
65 mph shown
68.2 mph actual
75 mph shown
78.7 mph actual
Common questions
- Will 215/55R17 fit instead of 205/50R17?
- Marginal fit — proceed with care. The 4.9% diameter change is between 3% and 5%. It can work, but expect noticeable speedometer error and check wheel-well clearance, scrub radius and gearing before committing. Your speedometer will read lower than your true speed. Overall diameter goes from 25.07″ to 26.31″, a change of +4.9%. 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 215/55R17?
- At an indicated 60 mph you would actually be travelling about 63.0 mph — a +4.9% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 205/50R17 and 215/55R17?
- 205/50R17 turns roughly 804 revolutions per mile; 215/55R17 turns roughly 767. That is a change of −38 revolutions per mile, which is what shifts odometer and speedometer readings.