145/60R14 vs 165/55R14
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 | 145/60R14 | 165/55R14 | Change |
|---|---|---|---|
| Overall height | 20.9" | 21.1" | +1.4 % |
| Sidewall | 3.43" | 3.57" | +4.3 % |
| Section width | 145 mm | 165 mm | +13.8 % |
| Circumference | 65.5" | 66.4" | +1.4 % |
| Revs per mile | 967 | 954 | -1.4 % |
| Axle height | 10.43" | 10.57" | +3.8 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 145/60R14. Fit 165/55R14 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 10,142 on the road, so it under-counts by 142. At a true 70 mph the first turns 1128 times a minute, the second 1113.