145/65R14 vs 165/55R14
Going from one to the other changes the overall height by -1.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 145/65R14 | 165/55R14 | Change |
|---|---|---|---|
| Overall height | 21.4" | 21.1" | -1.3 % |
| Sidewall | 3.71" | 3.57" | -3.7 % |
| Section width | 145 mm | 165 mm | +13.8 % |
| Circumference | 67.3" | 66.4" | -1.3 % |
| Revs per mile | 941 | 954 | +1.3 % |
| Axle height | 10.71" | 10.57" | -3.5 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 145/65R14. Fit 165/55R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.8 mph | -1.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,871 on the road, so it over-counts by 129. At a true 70 mph the first turns 1098 times a minute, the second 1113.