155/50R14 vs 165/50R14
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/50R14 | 165/50R14 | Change |
|---|---|---|---|
| Overall height | 20.1" | 20.5" | +2.0 % |
| Sidewall | 3.05" | 3.25" | +6.5 % |
| Section width | 155 mm | 165 mm | +6.5 % |
| Circumference | 63.2" | 64.4" | +2.0 % |
| Revs per mile | 1003 | 984 | -2.0 % |
| Axle height | 10.05" | 10.25" | +5.0 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 155/50R14. Fit 165/50R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,196 on the road, so it under-counts by 196. At a true 70 mph the first turns 1170 times a minute, the second 1148.