195/60R15 vs 185/55R16
New overall diameter
24.01″
was 24.21″
True speed at an indicated 60
59.5 mph
your speedo reads high
Revolutions per mile
840
was 833, +7
| Measurement | 195/60R15 | 185/55R16 | Change |
|---|---|---|---|
| Overall diameter | 24.21″ | 24.01″ | −0.20″ (−0.8%) |
| Sidewall height | 4.61″ (117.0 mm) | 4.01″ (101.8 mm) | −15.3 mm |
| Tread width | 195 mm | 185 mm | −10 mm |
| Circumference | 76.07″ | 75.44″ | −0.63″ |
| Revs per mile | 833 | 840 | +7 |
| Speedometer error | baseline | −0.8% | reads high |
Diameter overlay
195/60R15 185/55R16
Speedometer check
With 185/55R16 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
24.8 mph actual
35 mph shown
34.7 mph actual
45 mph shown
44.6 mph actual
55 mph shown
54.5 mph actual
65 mph shown
64.5 mph actual
75 mph shown
74.4 mph actual
Common questions
- Will 185/55R16 fit instead of 195/60R15?
- Diameter moves 0.8%, 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 24.21″ to 24.01″, a change of −0.8%. 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 185/55R16?
- At an indicated 60 mph you are really doing about 59.5 mph, a −0.8% error. The speedometer reads high, so you are going slower than it shows.
- What is the difference in revolutions per mile between 195/60R15 and 185/55R16?
- 195/60R15 turns about 833 times per mile and 185/55R16 turns about 840, a difference of +7. Your speedometer and odometer both count rotations, so this number is what throws them off.