195/45R16 vs 185/50R16
Going from one to the other changes the overall height by +1.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/45R16 | 185/50R16 | Change |
|---|---|---|---|
| Overall height | 22.9" | 23.3" | +1.6 % |
| Sidewall | 3.45" | 3.64" | +5.4 % |
| Section width | 195 mm | 185 mm | -5.1 % |
| Circumference | 72.0" | 73.1" | +1.6 % |
| Revs per mile | 880 | 866 | -1.6 % |
| Axle height | 11.45" | 11.64" | +4.8 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 195/45R16. Fit 185/50R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.8 mph | +0.8 |
| 70 mph | 71.1 mph | +1.1 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,163 on the road, so it under-counts by 163. At a true 70 mph the first turns 1027 times a minute, the second 1011.