155/70R17 vs 175/60R17
Going from one to the other changes the overall height by -1.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/70R17 | 175/60R17 | Change |
|---|---|---|---|
| Overall height | 25.5" | 25.3" | -1.1 % |
| Sidewall | 4.27" | 4.13" | -3.2 % |
| Section width | 155 mm | 175 mm | +12.9 % |
| Circumference | 80.2" | 79.4" | -1.1 % |
| Revs per mile | 790 | 798 | +1.1 % |
| Axle height | 12.77" | 12.63" | -3.5 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 155/70R17. Fit 175/60R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.7 mph | -0.3 |
| 50 mph | 49.5 mph | -0.5 |
| 70 mph | 69.2 mph | -0.8 |
| 90 mph | 89.0 mph | -1.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,892 on the road, so it over-counts by 108. At a true 70 mph the first turns 921 times a minute, the second 931.