195/70R15 vs 205/65R15
Going from one to the other changes the overall height by -1.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/70R15 | 205/65R15 | Change |
|---|---|---|---|
| Overall height | 25.7" | 25.5" | -1.0 % |
| Sidewall | 5.37" | 5.25" | -2.4 % |
| Section width | 195 mm | 205 mm | +5.1 % |
| Circumference | 80.9" | 80.1" | -1.0 % |
| Revs per mile | 783 | 791 | +1.0 % |
| Axle height | 12.87" | 12.75" | -3.3 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 195/70R15. Fit 205/65R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.5 mph | -0.5 |
| 70 mph | 69.3 mph | -0.7 |
| 90 mph | 89.1 mph | -0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,901 on the road, so it over-counts by 99. At a true 70 mph the first turns 914 times a minute, the second 923.