195/70R16 vs 185/75R16
Going from one to the other changes the overall height by +0.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 195/70R16 | 185/75R16 | Change |
|---|---|---|---|
| Overall height | 26.7" | 26.9" | +0.7 % |
| Sidewall | 5.37" | 5.46" | +1.6 % |
| Section width | 195 mm | 185 mm | -5.1 % |
| Circumference | 84.0" | 84.6" | +0.7 % |
| Revs per mile | 754 | 749 | -0.7 % |
| Axle height | 13.37" | 13.46" | +2.3 mm |
| Approved rim width | 5.5–7" | 5–6.5" | 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 195/70R16. Fit 185/75R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.2 mph | +0.2 |
| 50 mph | 50.3 mph | +0.3 |
| 70 mph | 70.5 mph | +0.5 |
| 90 mph | 90.6 mph | +0.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,066 on the road, so it under-counts by 66. At a true 70 mph the first turns 880 times a minute, the second 874.