195/55R16 vs 175/65R15
New overall diameter
23.96″
was 24.44″
True speed at an indicated 60
58.8 mph
your speedo reads high
Revolutions per mile
842
was 825, +17
| Measurement | 195/55R16 | 175/65R15 | Change |
|---|---|---|---|
| Overall diameter | 24.44″ | 23.96″ | −0.49″ (−2.0%) |
| Sidewall height | 4.22″ (107.3 mm) | 4.48″ (113.8 mm) | +6.5 mm |
| Tread width | 195 mm | 175 mm | −20 mm |
| Circumference | 76.80″ | 75.26″ | −1.53″ |
| Revs per mile | 825 | 842 | +17 |
| Speedometer error | baseline | −2.0% | reads high |
Diameter overlay
195/55R16 175/65R15
Speedometer check
With 175/65R15 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
24.5 mph actual
35 mph shown
34.3 mph actual
45 mph shown
44.1 mph actual
55 mph shown
53.9 mph actual
65 mph shown
63.7 mph actual
75 mph shown
73.5 mph actual
Common questions
- Will 175/65R15 fit instead of 195/55R16?
- Diameter moves 2.0%, comfortably inside the 3% rule. Your speedometer, ABS, traction control and gearing all stay in the range they were calibrated for. Your speedometer will read high, so you are going slower than it says. Overall diameter goes from 24.44″ to 23.96″, a change of −2.0%. 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 175/65R15?
- At an indicated 60 mph you are really doing about 58.8 mph, a −2.0% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 195/55R16 and 175/65R15?
- 195/55R16 turns about 825 times per mile and 175/65R15 turns about 842, a difference of +17. Your speedometer and odometer both count rotations, so this number is what throws them off.