165/65R13 vs 145/70R13
Going from one to the other changes the overall height by -2.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 165/65R13 | 145/70R13 | Change |
|---|---|---|---|
| Overall height | 21.4" | 21.0" | -2.1 % |
| Sidewall | 4.22" | 4.00" | -5.4 % |
| Section width | 165 mm | 145 mm | -12.1 % |
| Circumference | 67.4" | 65.9" | -2.1 % |
| Revs per mile | 940 | 961 | +2.1 % |
| Axle height | 10.72" | 10.50" | -5.8 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 165/65R13. Fit 145/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.5 mph | -1.5 |
| 90 mph | 88.1 mph | -1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,789 on the road, so it over-counts by 211. At a true 70 mph the first turns 1097 times a minute, the second 1121.