175/65R13 vs 155/70R13
Going from one to the other changes the overall height by -1.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 175/65R13 | 155/70R13 | Change |
|---|---|---|---|
| Overall height | 22.0" | 21.5" | -1.9 % |
| Sidewall | 4.48" | 4.27" | -4.6 % |
| Section width | 175 mm | 155 mm | -11.4 % |
| Circumference | 69.0" | 67.7" | -1.9 % |
| Revs per mile | 919 | 936 | +1.9 % |
| Axle height | 10.98" | 10.77" | -5.3 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 175/65R13. Fit 155/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.1 mph | -0.9 |
| 70 mph | 68.7 mph | -1.3 |
| 90 mph | 88.3 mph | -1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,812 on the road, so it over-counts by 188. At a true 70 mph the first turns 1072 times a minute, the second 1092.