185/60R15 vs 195/55R16
New overall diameter
24.44″
was 23.74″
True speed at an indicated 60
61.8 mph
your speedo reads low
Revolutions per mile
825
was 850, −24
| Measurement | 185/60R15 | 195/55R16 | Change |
|---|---|---|---|
| Overall diameter | 23.74″ | 24.44″ | +0.70″ (+3.0%) |
| Sidewall height | 4.37″ (111.0 mm) | 4.22″ (107.3 mm) | −3.8 mm |
| Tread width | 185 mm | 195 mm | +10 mm |
| Circumference | 74.58″ | 76.80″ | +2.21″ |
| Revs per mile | 850 | 825 | −24 |
| Speedometer error | baseline | +3.0% | reads low |
Diameter overlay
185/60R15 195/55R16
Speedometer check
With 195/55R16 fitted, when the speedometer shows the indicated speed, your actual speed is:
25 mph shown
25.7 mph actual
35 mph shown
36.0 mph actual
45 mph shown
46.3 mph actual
55 mph shown
56.6 mph actual
65 mph shown
66.9 mph actual
75 mph shown
77.2 mph actual
Common questions
- Will 195/55R16 fit instead of 185/60R15?
- Diameter moves 3.0%, 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 low, so you are going faster than it says. Overall diameter goes from 23.74″ to 24.44″, a change of +3.0%. 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 195/55R16?
- At an indicated 60 mph you are really doing about 61.8 mph, a +3.0% error. The speedometer reads low, so you are going faster than it shows.
- What is the difference in revolutions per mile between 185/60R15 and 195/55R16?
- 185/60R15 turns about 850 times per mile and 195/55R16 turns about 825, a difference of −24. Your speedometer and odometer both count rotations, so this number is what throws them off.