225/40R17 vs 215/45R17
Going from one to the other changes the overall height by +2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/40R17 | 215/45R17 | Change |
|---|---|---|---|
| Overall height | 24.1" | 24.6" | +2.2 % |
| Sidewall | 3.54" | 3.81" | +7.5 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 75.7" | 77.3" | +2.2 % |
| Revs per mile | 837 | 819 | -2.2 % |
| Axle height | 12.04" | 12.31" | +6.8 mm |
| Approved rim width | 6–8.5" | 6–8" | overlap 6–8" |
Both are approved on a rim 6" to 8" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 225/40R17. Fit 215/45R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 92.0 mph | +2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,221 on the road, so it under-counts by 221. At a true 70 mph the first turns 977 times a minute, the second 956.
What drivers reported
Nobody has filed a complaint naming 225/40R17. 215/45R17 carries 56.