155/60R15 vs 165/60R15
Going from one to the other changes the overall height by +2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/60R15 | 165/60R15 | Change |
|---|---|---|---|
| Overall height | 22.3" | 22.8" | +2.1 % |
| Sidewall | 3.66" | 3.90" | +6.5 % |
| Section width | 155 mm | 165 mm | +6.5 % |
| Circumference | 70.1" | 71.6" | +2.1 % |
| Revs per mile | 903 | 885 | -2.1 % |
| Axle height | 11.16" | 11.40" | +6.0 mm |
| Approved rim width | 4–5.5" | 4.5–6" | overlap 4.5–5.5" |
Both are approved on a rim 4.5" 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 155/60R15. Fit 165/60R15 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.5 mph | +1.5 |
| 90 mph | 91.9 mph | +1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,212 on the road, so it under-counts by 212. At a true 70 mph the first turns 1054 times a minute, the second 1032.