215/50R15 vs 205/55R15
Going from one to the other changes the overall height by +1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/50R15 | 205/55R15 | Change |
|---|---|---|---|
| Overall height | 23.5" | 23.9" | +1.8 % |
| Sidewall | 4.23" | 4.44" | +4.9 % |
| Section width | 215 mm | 205 mm | -4.7 % |
| Circumference | 73.7" | 75.0" | +1.8 % |
| Revs per mile | 860 | 845 | -1.8 % |
| Axle height | 11.73" | 11.94" | +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 215/50R15. Fit 205/55R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.6 mph | +1.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,176 on the road, so it under-counts by 176. At a true 70 mph the first turns 1003 times a minute, the second 985.
What drivers reported
Nobody has filed a complaint naming 215/50R15. 205/55R15 carries 7.