185/70R17 vs 195/70R17
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/70R17 | 195/70R17 | Change |
|---|---|---|---|
| Overall height | 27.2" | 27.7" | +2.0 % |
| Sidewall | 5.10" | 5.37" | +5.4 % |
| Section width | 185 mm | 195 mm | +5.4 % |
| Circumference | 85.4" | 87.2" | +2.0 % |
| Revs per mile | 742 | 727 | -2.0 % |
| Axle height | 13.60" | 13.87" | +7.0 mm |
| Approved rim width | 5–6.5" | 5.5–7" | overlap 5.5–6.5" |
Both are approved on a rim 5.5" to 6.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 185/70R17. Fit 195/70R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,203 on the road, so it under-counts by 203. At a true 70 mph the first turns 865 times a minute, the second 848.