215/50R20 vs 205/55R20
Going from one to the other changes the overall height by +1.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/50R20 | 205/55R20 | Change |
|---|---|---|---|
| Overall height | 28.5" | 28.9" | +1.5 % |
| Sidewall | 4.23" | 4.44" | +4.9 % |
| Section width | 215 mm | 205 mm | -4.7 % |
| Circumference | 89.4" | 90.7" | +1.5 % |
| Revs per mile | 709 | 698 | -1.5 % |
| Axle height | 14.23" | 14.44" | +5.3 mm |
| Approved rim width | 6–8" | 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 215/50R20. Fit 205/55R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.7 mph | +0.7 |
| 70 mph | 71.0 mph | +1.0 |
| 90 mph | 91.3 mph | +1.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,145 on the road, so it under-counts by 145. At a true 70 mph the first turns 827 times a minute, the second 815.
What drivers reported
215/50R20 carries 1 complaints. Nobody has filed one naming 205/55R20.