215/40R17 vs 205/40R17
Going from one to the other changes the overall height by -1.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/40R17 | 205/40R17 | Change |
|---|---|---|---|
| Overall height | 23.8" | 23.5" | -1.3 % |
| Sidewall | 3.39" | 3.23" | -4.7 % |
| Section width | 215 mm | 205 mm | -4.7 % |
| Circumference | 74.7" | 73.7" | -1.3 % |
| Revs per mile | 848 | 860 | +1.3 % |
| Axle height | 11.89" | 11.73" | -4.0 mm |
| Approved rim width | 6–8" | 5.5–7.5" | 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 215/40R17. Fit 205/40R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.3 mph | -0.7 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.8 mph | -1.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,868 on the road, so it over-counts by 132. At a true 70 mph the first turns 990 times a minute, the second 1003.
What drivers reported
215/40R17 carries 2 complaints. Nobody has filed one naming 205/40R17.