205/40R16 vs 225/40R16
Going from one to the other changes the overall height by +2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/40R16 | 225/40R16 | Change |
|---|---|---|---|
| Overall height | 22.5" | 23.1" | +2.8 % |
| Sidewall | 3.23" | 3.54" | +9.8 % |
| Section width | 205 mm | 225 mm | +9.8 % |
| Circumference | 70.5" | 72.5" | +2.8 % |
| Revs per mile | 898 | 874 | -2.8 % |
| Axle height | 11.23" | 11.54" | +8.0 mm |
| Approved rim width | 5.5–7.5" | 6–8.5" | 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 205/40R16. Fit 225/40R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.5 mph | +2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,281 on the road, so it under-counts by 281. At a true 70 mph the first turns 1048 times a minute, the second 1019.