175/55R15 vs 165/60R15
Going from one to the other changes the overall height by +1.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/55R15 | 165/60R15 | Change |
|---|---|---|---|
| Overall height | 22.6" | 22.8" | +1.0 % |
| Sidewall | 3.79" | 3.90" | +2.9 % |
| Section width | 175 mm | 165 mm | -5.7 % |
| Circumference | 70.9" | 71.6" | +1.0 % |
| Revs per mile | 893 | 885 | -1.0 % |
| Axle height | 11.29" | 11.40" | +2.8 mm |
| Approved rim width | 5–6" | 4.5–6" | overlap 5–6" |
Both are approved on a rim 5" to 6" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 175/55R15. Fit 165/60R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.5 mph | +0.5 |
| 70 mph | 70.7 mph | +0.7 |
| 90 mph | 90.9 mph | +0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,096 on the road, so it under-counts by 96. At a true 70 mph the first turns 1042 times a minute, the second 1032.