145/85R13 vs 165/75R13
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 | 145/85R13 | 165/75R13 | Change |
|---|---|---|---|
| Overall height | 22.7" | 22.7" | +0.2 % |
| Sidewall | 4.85" | 4.87" | +0.4 % |
| Section width | 145 mm | 165 mm | +13.8 % |
| Circumference | 71.3" | 71.5" | +0.2 % |
| Revs per mile | 888 | 887 | -0.2 % |
| Axle height | 11.35" | 11.37" | +0.5 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 145/85R13. Fit 165/75R13 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 | 70.1 mph | +0.1 |
| 90 mph | 90.2 mph | +0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,017 on the road, so it under-counts by 17. At a true 70 mph the first turns 1036 times a minute, the second 1035.