205/65R20 vs 225/55R20
Going from one to the other changes the overall height by -2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/65R20 | 225/55R20 | Change |
|---|---|---|---|
| Overall height | 30.5" | 29.7" | -2.5 % |
| Sidewall | 5.25" | 4.87" | -7.1 % |
| Section width | 205 mm | 225 mm | +9.8 % |
| Circumference | 95.8" | 93.4" | -2.5 % |
| Revs per mile | 661 | 678 | +2.5 % |
| Axle height | 15.25" | 14.87" | -9.5 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 205/65R20. Fit 225/55R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.3 mph | -1.7 |
| 90 mph | 87.8 mph | -2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,755 on the road, so it over-counts by 245. At a true 70 mph the first turns 772 times a minute, the second 791.
What drivers reported
Nobody has filed a complaint naming 205/65R20. 225/55R20 carries 2.