255/65R17 vs 225/65R17
New overall diameter
28.52″
was 30.05″
True speed at an indicated 60
56.9 mph
your speedo reads high
Revolutions per mile
707
was 671, +36
| 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?
- 5.1% is past the 5% mark, which is where this stops being a tire choice and starts being a project. Expect rubbing, meaningful speedometer error, and extra load on ABS, stability control and the drivetrain. Recalibration is the usual fix. Your speedometer will read high, so you are going slower than it says. Overall diameter goes from 30.05″ to 28.52″, a change of −5.1%. The rule of thumb most shops use: under 3% is fine, 3 to 5% needs a clearance check, over 5% needs recalibration.
- How far off will my speedometer read on 225/65R17?
- At an indicated 60 mph you are really doing 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 about 671 times per mile and 225/65R17 turns about 707, a difference of +36. Your speedometer and odometer both count rotations, so this number is what throws them off.