155/60R14 vs 175/55R14
Going from one to the other changes the overall height by +1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/60R14 | 175/55R14 | Change |
|---|---|---|---|
| Overall height | 21.3" | 21.6" | +1.2 % |
| Sidewall | 3.66" | 3.79" | +3.5 % |
| Section width | 155 mm | 175 mm | +12.9 % |
| Circumference | 67.0" | 67.8" | +1.2 % |
| Revs per mile | 946 | 935 | -1.2 % |
| Axle height | 10.66" | 10.79" | +3.3 mm |
| Approved rim width | 4–5.5" | 5–6" | overlap 5–5.5" |
Both are approved on a rim 5" to 5.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 155/60R14. Fit 175/55R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.8 mph | +0.8 |
| 90 mph | 91.1 mph | +1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,120 on the road, so it under-counts by 120. At a true 70 mph the first turns 1103 times a minute, the second 1090.