155/60R13 vs 135/70R13
Going from one to the other changes the overall height by +0.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/60R13 | 135/70R13 | Change |
|---|---|---|---|
| Overall height | 20.3" | 20.4" | +0.6 % |
| Sidewall | 3.66" | 3.72" | +1.6 % |
| Section width | 155 mm | 135 mm | -12.9 % |
| Circumference | 63.8" | 64.2" | +0.6 % |
| Revs per mile | 992 | 987 | -0.6 % |
| Axle height | 10.16" | 10.22" | +1.5 mm |
| Approved rim width | 4–5.5" | 3.5–5" | overlap 4–5" |
Both are approved on a rim 4" to 5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 155/60R13. Fit 135/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.2 mph | +0.2 |
| 50 mph | 50.3 mph | +0.3 |
| 70 mph | 70.4 mph | +0.4 |
| 90 mph | 90.5 mph | +0.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,058 on the road, so it under-counts by 58. At a true 70 mph the first turns 1158 times a minute, the second 1151.