225/55R16 vs 205/65R16
Going from one to the other changes the overall height by +2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 225/55R16 | 205/65R16 | Change |
|---|---|---|---|
| Overall height | 25.7" | 26.5" | +2.9 % |
| Sidewall | 4.87" | 5.25" | +7.7 % |
| Section width | 225 mm | 205 mm | -8.9 % |
| Circumference | 80.9" | 83.2" | +2.9 % |
| Revs per mile | 783 | 761 | -2.9 % |
| Axle height | 12.87" | 13.25" | +9.5 mm |
| Approved rim width | 6–8.5" | 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 225/55R16. Fit 205/65R16 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.5 mph | +1.5 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,291 on the road, so it under-counts by 291. At a true 70 mph the first turns 914 times a minute, the second 888.