185/50R17 vs 185/55R17
Going from one to the other changes the overall height by +3.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 185/50R17 | 185/55R17 | Change |
|---|---|---|---|
| Overall height | 24.3" | 25.0" | +3.0 % |
| Sidewall | 3.64" | 4.01" | +10.0 % |
| Section width | 185 mm | 185 mm | 0.0 % |
| Circumference | 76.3" | 78.6" | +3.0 % |
| Revs per mile | 831 | 806 | -3.0 % |
| Axle height | 12.14" | 12.51" | +9.3 mm |
| Approved rim width | 5–6.5" | 5–6.5" | overlap 5–6.5" |
Both are approved on a rim 5" to 6.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 185/50R17. Fit 185/55R17 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 | 72.1 mph | +2.1 |
| 90 mph | 92.7 mph | +2.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,300 on the road, so it under-counts by 300. At a true 70 mph the first turns 969 times a minute, the second 941.
What drivers reported
Nobody has filed a complaint naming 185/50R17. 185/55R17 carries 3.