145/65R13 vs 145/70R13
Going from one to the other changes the overall height by +2.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 145/65R13 | 145/70R13 | Change |
|---|---|---|---|
| Overall height | 20.4" | 21.0" | +2.8 % |
| Sidewall | 3.71" | 4.00" | +7.7 % |
| Section width | 145 mm | 145 mm | 0.0 % |
| Circumference | 64.2" | 65.9" | +2.8 % |
| Revs per mile | 988 | 961 | -2.8 % |
| Axle height | 10.21" | 10.50" | +7.3 mm |
| Approved rim width | 4–5.5" | 4–5.5" | overlap 4–5.5" |
Both are approved on a rim 4" 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 145/65R13. Fit 145/70R13 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.5 mph | +2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,280 on the road, so it under-counts by 280. At a true 70 mph the first turns 1152 times a minute, the second 1121.