205/85R17 vs 215/80R17
Going from one to the other changes the overall height by -0.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/85R17 | 215/80R17 | Change |
|---|---|---|---|
| Overall height | 30.7" | 30.5" | -0.6 % |
| Sidewall | 6.86" | 6.77" | -1.3 % |
| Section width | 205 mm | 215 mm | +4.9 % |
| Circumference | 96.5" | 96.0" | -0.6 % |
| Revs per mile | 657 | 660 | +0.6 % |
| Axle height | 15.36" | 15.27" | -2.3 mm |
| Approved rim width | 5.5–7.5" | 6–8" | overlap 6–7.5" |
Both are approved on a rim 6" to 7.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 205/85R17. Fit 215/80R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.8 mph | -0.2 |
| 50 mph | 49.7 mph | -0.3 |
| 70 mph | 69.6 mph | -0.4 |
| 90 mph | 89.5 mph | -0.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,942 on the road, so it over-counts by 58. At a true 70 mph the first turns 766 times a minute, the second 770.