225/35R19 vs 215/40R19
Going from one to the other changes the overall height by +2.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/35R19 | 215/40R19 | Change |
|---|---|---|---|
| Overall height | 25.2" | 25.8" | +2.3 % |
| Sidewall | 3.10" | 3.39" | +9.2 % |
| Section width | 225 mm | 215 mm | -4.4 % |
| Circumference | 79.2" | 81.0" | +2.3 % |
| Revs per mile | 800 | 783 | -2.3 % |
| Axle height | 12.60" | 12.89" | +7.3 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 225/35R19. Fit 215/40R19 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 | 71.6 mph | +1.6 |
| 90 mph | 92.0 mph | +2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,227 on the road, so it under-counts by 227. At a true 70 mph the first turns 934 times a minute, the second 913.