165/70R16 vs 185/65R16
Going from one to the other changes the overall height by +1.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 165/70R16 | 185/65R16 | Change |
|---|---|---|---|
| Overall height | 25.1" | 25.5" | +1.5 % |
| Sidewall | 4.55" | 4.73" | +4.1 % |
| Section width | 165 mm | 185 mm | +12.1 % |
| Circumference | 78.8" | 80.0" | +1.5 % |
| Revs per mile | 804 | 792 | -1.5 % |
| Axle height | 12.55" | 12.73" | +4.8 mm |
| Approved rim width | 4.5–6" | 5–6.5" | overlap 5–6" |
Both are approved on a rim 5" to 6" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 165/70R16. Fit 185/65R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.7 mph | +0.7 |
| 70 mph | 71.0 mph | +1.0 |
| 90 mph | 91.3 mph | +1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,149 on the road, so it under-counts by 149. At a true 70 mph the first turns 938 times a minute, the second 924.