155/85R13 vs 165/80R13
Going from one to the other changes the overall height by +0.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/85R13 | 165/80R13 | Change |
|---|---|---|---|
| Overall height | 23.4" | 23.4" | +0.1 % |
| Sidewall | 5.19" | 5.20" | +0.2 % |
| Section width | 155 mm | 165 mm | +6.5 % |
| Circumference | 73.4" | 73.5" | +0.1 % |
| Revs per mile | 863 | 862 | -0.1 % |
| Axle height | 11.69" | 11.70" | +0.3 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 155/85R13. Fit 165/80R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.0 mph | +0.0 |
| 50 mph | 50.0 mph | +0.0 |
| 70 mph | 70.1 mph | +0.1 |
| 90 mph | 90.1 mph | +0.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,008 on the road, so it under-counts by 8. At a true 70 mph the first turns 1007 times a minute, the second 1006.