215/70R15 vs 195/75R15
Going from one to the other changes the overall height by -1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/70R15 | 195/75R15 | Change |
|---|---|---|---|
| Overall height | 26.9" | 26.5" | -1.2 % |
| Sidewall | 5.93" | 5.76" | -2.8 % |
| Section width | 215 mm | 195 mm | -9.3 % |
| Circumference | 84.4" | 83.3" | -1.2 % |
| Revs per mile | 751 | 761 | +1.2 % |
| Axle height | 13.43" | 13.26" | -4.3 mm |
| Approved rim width | 6–8" | 5.5–7" | overlap 6–7" |
Both are approved on a rim 6" to 7" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/70R15. Fit 195/75R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,875 on the road, so it over-counts by 125. At a true 70 mph the first turns 876 times a minute, the second 887.