175/60R13 vs 155/70R13
Going from one to the other changes the overall height by +1.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/60R13 | 155/70R13 | Change |
|---|---|---|---|
| Overall height | 21.3" | 21.5" | +1.3 % |
| Sidewall | 4.13" | 4.27" | +3.3 % |
| Section width | 175 mm | 155 mm | -11.4 % |
| Circumference | 66.8" | 67.7" | +1.3 % |
| Revs per mile | 948 | 936 | -1.3 % |
| Axle height | 10.63" | 10.77" | +3.5 mm |
| Approved rim width | 5–6" | 4–5.5" | overlap 5–5.5" |
Both are approved on a rim 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 175/60R13. Fit 155/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.4 mph | +0.4 |
| 50 mph | 50.6 mph | +0.6 |
| 70 mph | 70.9 mph | +0.9 |
| 90 mph | 91.2 mph | +1.2 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,130 on the road, so it under-counts by 130. At a true 70 mph the first turns 1106 times a minute, the second 1092.