175/60R15 vs 165/65R15
Going from one to the other changes the overall height by +0.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/60R15 | 165/65R15 | Change |
|---|---|---|---|
| Overall height | 23.3" | 23.4" | +0.8 % |
| Sidewall | 4.13" | 4.22" | +2.1 % |
| Section width | 175 mm | 165 mm | -5.7 % |
| Circumference | 73.1" | 73.7" | +0.8 % |
| Revs per mile | 867 | 860 | -0.8 % |
| Axle height | 11.63" | 11.72" | +2.3 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 175/60R15. Fit 165/65R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.2 mph | +0.2 |
| 50 mph | 50.4 mph | +0.4 |
| 70 mph | 70.5 mph | +0.5 |
| 90 mph | 90.7 mph | +0.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,076 on the road, so it under-counts by 76. At a true 70 mph the first turns 1011 times a minute, the second 1004.