215/75R17 vs 195/85R17
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 | 215/75R17 | 195/85R17 | Change |
|---|---|---|---|
| Overall height | 29.7" | 30.1" | +1.2 % |
| Sidewall | 6.35" | 6.53" | +2.8 % |
| Section width | 215 mm | 195 mm | -9.3 % |
| Circumference | 93.3" | 94.4" | +1.2 % |
| Revs per mile | 679 | 671 | -1.2 % |
| Axle height | 14.85" | 15.03" | +4.5 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 215/75R17. Fit 195/85R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.8 mph | +0.8 |
| 90 mph | 91.1 mph | +1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,119 on the road, so it under-counts by 119. At a true 70 mph the first turns 792 times a minute, the second 783.