165/60R13 vs 145/70R13
Going from one to the other changes the overall height by +0.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 165/60R13 | 145/70R13 | Change |
|---|---|---|---|
| Overall height | 20.8" | 21.0" | +0.9 % |
| Sidewall | 3.90" | 4.00" | +2.5 % |
| Section width | 165 mm | 145 mm | -12.1 % |
| Circumference | 65.3" | 65.9" | +0.9 % |
| Revs per mile | 970 | 961 | -0.9 % |
| Axle height | 10.40" | 10.50" | +2.5 mm |
| Approved rim width | 4.5–6" | 4–5.5" | overlap 4.5–5.5" |
Both are approved on a rim 4.5" 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 165/60R13. Fit 145/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.5 mph | +0.5 |
| 70 mph | 70.7 mph | +0.7 |
| 90 mph | 90.9 mph | +0.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,095 on the road, so it under-counts by 95. At a true 70 mph the first turns 1131 times a minute, the second 1121.