145/85R13 vs 155/85R13
Going from one to the other changes the overall height by +2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 145/85R13 | 155/85R13 | Change |
|---|---|---|---|
| Overall height | 22.7" | 23.4" | +2.9 % |
| Sidewall | 4.85" | 5.19" | +6.9 % |
| Section width | 145 mm | 155 mm | +6.9 % |
| Circumference | 71.3" | 73.4" | +2.9 % |
| Revs per mile | 888 | 863 | -2.9 % |
| Axle height | 11.35" | 11.69" | +8.5 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 145/85R13. Fit 155/85R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.5 mph | +1.5 |
| 70 mph | 72.1 mph | +2.1 |
| 90 mph | 92.7 mph | +2.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,295 on the road, so it under-counts by 295. At a true 70 mph the first turns 1036 times a minute, the second 1007.