265/65R17 vs 235/65R17
New overall diameter
29.03″
was 30.56″
True speed at an indicated 60
57.0 mph
your speedo reads high
Revolutions per mile
695
was 660, +35
| Measurement | 265/65R17 | 235/65R17 | Change |
|---|---|---|---|
| Overall diameter | 30.56″ | 29.03″ | −1.54″ (−5.0%) |
| Sidewall height | 6.78″ (172.3 mm) | 6.01″ (152.8 mm) | −19.5 mm |
| Tread width | 265 mm | 235 mm | −30 mm |
| Circumference | 96.02″ | 91.19″ | −4.82″ |
| Revs per mile | 660 | 695 | +35 |
| Speedometer error | baseline | −5.0% | reads high |
Diameter overlay
265/65R17 235/65R17
Speedometer check
With 235/65R17 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 235/65R17 fit instead of 265/65R17?
- 5.0% 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 30.56″ to 29.03″, a change of −5.0%. 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 235/65R17?
- At an indicated 60 mph you are really doing about 57.0 mph, a −5.0% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 265/65R17 and 235/65R17?
- 265/65R17 turns about 660 times per mile and 235/65R17 turns about 695, a difference of +35. Your speedometer and odometer both count rotations, so this number is what throws them off.