125/70R16 vs 125/65R16
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 | 125/70R16 | 125/65R16 | Change |
|---|---|---|---|
| Overall height | 22.9" | 22.4" | -2.1 % |
| Sidewall | 3.44" | 3.20" | -7.1 % |
| Section width | 125 mm | 125 mm | 0.0 % |
| Circumference | 71.9" | 70.4" | -2.1 % |
| Revs per mile | 881 | 900 | +2.1 % |
| Axle height | 11.44" | 11.20" | -6.3 mm |
| Approved rim width | 3.5–4.5" | 3.5–4.5" | overlap 3.5–4.5" |
Both are approved on a rim 3.5" 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 125/70R16. Fit 125/65R16 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 9,785 on the road, so it over-counts by 215. At a true 70 mph the first turns 1028 times a minute, the second 1051.
What drivers reported
125/70R16 carries 10 complaints. Nobody has filed one naming 125/65R16.