125/70R17 vs 145/65R17
Going from one to the other changes the overall height by +2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 125/70R17 | 145/65R17 | Change |
|---|---|---|---|
| Overall height | 23.9" | 24.4" | +2.2 % |
| Sidewall | 3.44" | 3.71" | +7.7 % |
| Section width | 125 mm | 145 mm | +16.0 % |
| Circumference | 75.1" | 76.7" | +2.2 % |
| Revs per mile | 844 | 826 | -2.2 % |
| Axle height | 11.94" | 12.21" | +6.8 mm |
| Approved rim width | 3.5–4.5" | 4–5.5" | overlap 4–4.5" |
Both are approved on a rim 4" to 4.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 125/70R17. Fit 145/65R17 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 | 92.0 mph | +2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,222 on the road, so it under-counts by 222. At a true 70 mph the first turns 985 times a minute, the second 963.
What drivers reported
125/70R17 carries 1 complaints. Nobody has filed one naming 145/65R17.