155/70R13 vs 135/85R13
Going from one to the other changes the overall height by +2.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 155/70R13 | 135/85R13 | Change |
|---|---|---|---|
| Overall height | 21.5" | 22.0" | +2.3 % |
| Sidewall | 4.27" | 4.52" | +5.8 % |
| Section width | 155 mm | 135 mm | -12.9 % |
| Circumference | 67.7" | 69.2" | +2.3 % |
| Revs per mile | 936 | 915 | -2.3 % |
| Axle height | 10.77" | 11.02" | +6.3 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 155/70R13. Fit 135/85R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.6 mph | +1.6 |
| 90 mph | 92.1 mph | +2.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,228 on the road, so it under-counts by 228. At a true 70 mph the first turns 1092 times a minute, the second 1068.