195/60R15 vs 205/55R15
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 | 195/60R15 | 205/55R15 | Change |
|---|---|---|---|
| Overall height | 24.2" | 23.9" | -1.4 % |
| Sidewall | 4.61" | 4.44" | -3.6 % |
| Section width | 195 mm | 205 mm | +5.1 % |
| Circumference | 76.1" | 75.0" | -1.4 % |
| Revs per mile | 833 | 845 | +1.4 % |
| Axle height | 12.11" | 11.94" | -4.3 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 195/60R15. Fit 205/55R15 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 | 88.8 mph | -1.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,862 on the road, so it over-counts by 138. At a true 70 mph the first turns 972 times a minute, the second 985.