195/50R16 vs 185/55R16
Going from one to the other changes the overall height by +1.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/50R16 | 185/55R16 | Change |
|---|---|---|---|
| Overall height | 23.7" | 24.0" | +1.4 % |
| Sidewall | 3.84" | 4.01" | +4.4 % |
| Section width | 195 mm | 185 mm | -5.1 % |
| Circumference | 74.4" | 75.4" | +1.4 % |
| Revs per mile | 852 | 840 | -1.4 % |
| Axle height | 11.84" | 12.01" | +4.3 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 195/50R16. Fit 185/55R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.7 mph | +0.7 |
| 70 mph | 71.0 mph | +1.0 |
| 90 mph | 91.3 mph | +1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,141 on the road, so it under-counts by 141. At a true 70 mph the first turns 994 times a minute, the second 980.