155/70R14 vs 165/70R14
Going from one to the other changes the overall height by +2.4 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/70R14 | 165/70R14 | Change |
|---|---|---|---|
| Overall height | 22.5" | 23.1" | +2.4 % |
| Sidewall | 4.27" | 4.55" | +6.5 % |
| Section width | 155 mm | 165 mm | +6.5 % |
| Circumference | 70.8" | 72.6" | +2.4 % |
| Revs per mile | 895 | 873 | -2.4 % |
| Axle height | 11.27" | 11.55" | +7.0 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 155/70R14. Fit 165/70R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.2 mph | +1.2 |
| 70 mph | 71.7 mph | +1.7 |
| 90 mph | 92.2 mph | +2.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,244 on the road, so it under-counts by 244. At a true 70 mph the first turns 1044 times a minute, the second 1019.