145/85R14 vs 155/80R14
Going from one to the other changes the overall height by +0.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 145/85R14 | 155/80R14 | Change |
|---|---|---|---|
| Overall height | 23.7" | 23.8" | +0.2 % |
| Sidewall | 4.85" | 4.88" | +0.6 % |
| Section width | 145 mm | 155 mm | +6.9 % |
| Circumference | 74.5" | 74.7" | +0.2 % |
| Revs per mile | 851 | 849 | -0.2 % |
| Axle height | 11.85" | 11.88" | +0.8 mm |
| Approved rim width | 4–5.5" | 4–5.5" | overlap 4–5.5" |
Both are approved on a rim 4" 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 145/85R14. Fit 155/80R14 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.1 mph | +0.1 |
| 50 mph | 50.1 mph | +0.1 |
| 70 mph | 70.2 mph | +0.2 |
| 90 mph | 90.2 mph | +0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,025 on the road, so it under-counts by 25. At a true 70 mph the first turns 993 times a minute, the second 990.