185/85R13 vs 195/80R13
Going from one to the other changes the overall height by -0.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/85R13 | 195/80R13 | Change |
|---|---|---|---|
| Overall height | 25.4" | 25.3" | -0.4 % |
| Sidewall | 6.19" | 6.14" | -0.8 % |
| Section width | 185 mm | 195 mm | +5.4 % |
| Circumference | 79.7" | 79.4" | -0.4 % |
| Revs per mile | 795 | 798 | +0.4 % |
| Axle height | 12.69" | 12.64" | -1.3 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 185/85R13. Fit 195/80R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.8 mph | -0.2 |
| 70 mph | 69.7 mph | -0.3 |
| 90 mph | 89.7 mph | -0.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,961 on the road, so it over-counts by 39. At a true 70 mph the first turns 927 times a minute, the second 931.