255/65R17 vs 225/65R17
New overall diameter
28.52″
was 30.05″
True speed at an indicated 60
56.9 mph
speedometer reads high
Revolutions per mile
707
was 671 · +36
Switching from 255/65R17 to 225/65R17? Everything that changes is below — sidewall, tread width, circumference, revolutions per mile and speedometer error at road speeds.
| Measurement | 255/65R17 | 225/65R17 | Change |
|---|---|---|---|
| Overall diameter | 30.05″ | 28.52″ | −1.54″ (−5.1%) |
| Sidewall height | 6.53″ (165.8 mm) | 5.76″ (146.3 mm) | −19.5 mm |
| Tread width | 255 mm | 225 mm | −30 mm |
| Circumference | 94.41″ | 89.58″ | −4.82″ |
| Revs per mile | 671 | 707 | +36 |
| Speedometer error | baseline | −5.1% | reads high |
Diameter overlay
255/65R17 225/65R17
Speedometer check
With 225/65R17 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
23.7 mph actual
35 mph shown
33.2 mph actual
45 mph shown
42.7 mph actual
55 mph shown
52.2 mph actual
65 mph shown
61.7 mph actual
75 mph shown
71.2 mph actual
Common questions
- Will 225/65R17 fit instead of 255/65R17?
- Not recommended. A 5.1% diameter change exceeds the 5% rule. Expect significant speedometer error, potential clearance and rubbing issues, and stress on ABS, stability control and drivetrain components. Your speedometer will read higher than your true speed. Overall diameter goes from 30.05″ to 28.52″, a change of −5.1%. 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 225/65R17?
- At an indicated 60 mph you would actually be travelling about 56.9 mph — a −5.1% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 255/65R17 and 225/65R17?
- 255/65R17 turns roughly 671 revolutions per mile; 225/65R17 turns roughly 707. That is a change of +36 revolutions per mile, which is what shifts odometer and speedometer readings.