155/80R13 vs 145/85R13
Going from one to the other changes the overall height by -0.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/80R13 | 145/85R13 | Change |
|---|---|---|---|
| Overall height | 22.8" | 22.7" | -0.3 % |
| Sidewall | 4.88" | 4.85" | -0.6 % |
| Section width | 155 mm | 145 mm | -6.5 % |
| Circumference | 71.5" | 71.3" | -0.3 % |
| Revs per mile | 886 | 888 | +0.3 % |
| Axle height | 11.38" | 11.35" | -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 155/80R13. Fit 145/85R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.9 mph | -0.1 |
| 50 mph | 49.9 mph | -0.1 |
| 70 mph | 69.8 mph | -0.2 |
| 90 mph | 89.8 mph | -0.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,974 on the road, so it over-counts by 26. At a true 70 mph the first turns 1034 times a minute, the second 1036.
What drivers reported
155/80R13 carries 4 complaints. Nobody has filed one naming 145/85R13.