195/60R16 vs 185/60R16
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/60R16 | 185/60R16 | Change |
|---|---|---|---|
| Overall height | 25.2" | 24.7" | -1.9 % |
| Sidewall | 4.61" | 4.37" | -5.1 % |
| Section width | 195 mm | 185 mm | -5.1 % |
| Circumference | 79.2" | 77.7" | -1.9 % |
| Revs per mile | 800 | 815 | +1.9 % |
| Axle height | 12.61" | 12.37" | -6.0 mm |
| Approved rim width | 5.5–7" | 5–6.5" | overlap 5.5–6.5" |
Both are approved on a rim 5.5" to 6.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 195/60R16. Fit 185/60R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,813 on the road, so it over-counts by 187. At a true 70 mph the first turns 933 times a minute, the second 951.