145/70R13 vs 155/70R13
Going from one to the other changes the overall height by +2.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 145/70R13 | 155/70R13 | Change |
|---|---|---|---|
| Overall height | 21.0" | 21.5" | +2.6 % |
| Sidewall | 4.00" | 4.27" | +6.9 % |
| Section width | 145 mm | 155 mm | +6.9 % |
| Circumference | 65.9" | 67.7" | +2.6 % |
| Revs per mile | 961 | 936 | -2.6 % |
| Axle height | 10.50" | 10.77" | +7.0 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 145/70R13. Fit 155/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.3 mph | +1.3 |
| 70 mph | 71.8 mph | +1.8 |
| 90 mph | 92.4 mph | +2.4 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,263 on the road, so it under-counts by 263. At a true 70 mph the first turns 1121 times a minute, the second 1092.