195/45R14 vs 205/40R14
Going from one to the other changes the overall height by -2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/45R14 | 205/40R14 | Change |
|---|---|---|---|
| Overall height | 20.9" | 20.5" | -2.2 % |
| Sidewall | 3.45" | 3.23" | -6.6 % |
| Section width | 195 mm | 205 mm | +5.1 % |
| Circumference | 65.7" | 64.3" | -2.2 % |
| Revs per mile | 965 | 986 | +2.2 % |
| Axle height | 10.45" | 10.23" | -5.8 mm |
| Approved rim width | 5.5–7" | 5.5–7.5" | 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 195/45R14. Fit 205/40R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,783 on the road, so it over-counts by 217. At a true 70 mph the first turns 1125 times a minute, the second 1150.