215/80R15 vs 195/85R15
Going from one to the other changes the overall height by -1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/80R15 | 195/85R15 | Change |
|---|---|---|---|
| Overall height | 28.5" | 28.1" | -1.7 % |
| Sidewall | 6.77" | 6.53" | -3.6 % |
| Section width | 215 mm | 195 mm | -9.3 % |
| Circumference | 89.7" | 88.1" | -1.7 % |
| Revs per mile | 707 | 719 | +1.7 % |
| Axle height | 14.27" | 14.03" | -6.3 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 215/80R15. Fit 195/85R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.5 mph | -0.5 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.8 mph | -1.2 |
| 90 mph | 88.4 mph | -1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,828 on the road, so it over-counts by 172. At a true 70 mph the first turns 824 times a minute, the second 839.