205/40R16 vs 195/40R16
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 | 205/40R16 | 195/40R16 | Change |
|---|---|---|---|
| Overall height | 22.5" | 22.1" | -1.4 % |
| Sidewall | 3.23" | 3.07" | -4.9 % |
| Section width | 205 mm | 195 mm | -4.9 % |
| Circumference | 70.5" | 69.6" | -1.4 % |
| Revs per mile | 898 | 911 | +1.4 % |
| Axle height | 11.23" | 11.07" | -4.0 mm |
| Approved rim width | 5.5–7.5" | 5.5–7" | overlap 5.5–7" |
Both are approved on a rim 5.5" to 7" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 205/40R16. Fit 195/40R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.3 mph | -0.7 |
| 70 mph | 69.0 mph | -1.0 |
| 90 mph | 88.7 mph | -1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,860 on the road, so it over-counts by 140. At a true 70 mph the first turns 1048 times a minute, the second 1063.