175/55R17 vs 155/65R17
Going from one to the other changes the overall height by +1.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/55R17 | 155/65R17 | Change |
|---|---|---|---|
| Overall height | 24.6" | 24.9" | +1.4 % |
| Sidewall | 3.79" | 3.97" | +4.7 % |
| Section width | 175 mm | 155 mm | -11.4 % |
| Circumference | 77.2" | 78.3" | +1.4 % |
| Revs per mile | 821 | 809 | -1.4 % |
| Axle height | 12.29" | 12.47" | +4.5 mm |
| Approved rim width | 5–6" | 4–5.5" | 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 175/55R17. Fit 155/65R17 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 10,144 on the road, so it under-counts by 144. At a true 70 mph the first turns 957 times a minute, the second 944.