205/55R15 vs 195/55R15
Going from one to the other changes the overall height by -1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/55R15 | 195/55R15 | Change |
|---|---|---|---|
| Overall height | 23.9" | 23.4" | -1.8 % |
| Sidewall | 4.44" | 4.22" | -4.9 % |
| Section width | 205 mm | 195 mm | -4.9 % |
| Circumference | 75.0" | 73.7" | -1.8 % |
| Revs per mile | 845 | 860 | +1.8 % |
| Axle height | 11.94" | 11.72" | -5.5 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 205/55R15. Fit 195/55R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,819 on the road, so it over-counts by 181. At a true 70 mph the first turns 985 times a minute, the second 1004.