195/70R15 vs 205/70R15
Going from one to the other changes the overall height by +2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/70R15 | 205/70R15 | Change |
|---|---|---|---|
| Overall height | 25.7" | 26.3" | +2.1 % |
| Sidewall | 5.37" | 5.65" | +5.1 % |
| Section width | 195 mm | 205 mm | +5.1 % |
| Circumference | 80.9" | 82.6" | +2.1 % |
| Revs per mile | 783 | 767 | -2.1 % |
| Axle height | 12.87" | 13.15" | +7.0 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 195/70R15. Fit 205/70R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 91.9 mph | +1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,214 on the road, so it under-counts by 214. At a true 70 mph the first turns 914 times a minute, the second 895.