205/70R20 vs 225/60R20
Going from one to the other changes the overall height by -2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 205/70R20 | 225/60R20 | Change |
|---|---|---|---|
| Overall height | 31.3" | 30.6" | -2.1 % |
| Sidewall | 5.65" | 5.31" | -5.9 % |
| Section width | 205 mm | 225 mm | +9.8 % |
| Circumference | 98.3" | 96.2" | -2.1 % |
| Revs per mile | 644 | 658 | +2.1 % |
| Axle height | 15.65" | 15.31" | -8.5 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 205/70R20. Fit 225/60R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,786 on the road, so it over-counts by 214. At a true 70 mph the first turns 752 times a minute, the second 768.
What drivers reported
205/70R20 carries 2 complaints. Nobody has filed one naming 225/60R20.