145/65R17 vs 135/65R17
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 | 145/65R17 | 135/65R17 | Change |
|---|---|---|---|
| Overall height | 24.4" | 23.9" | -2.1 % |
| Sidewall | 3.71" | 3.45" | -6.9 % |
| Section width | 145 mm | 135 mm | -6.9 % |
| Circumference | 76.7" | 75.1" | -2.1 % |
| Revs per mile | 826 | 844 | +2.1 % |
| Axle height | 12.21" | 11.95" | -6.5 mm |
| Approved rim width | 4–5.5" | 3.5–5" | overlap 4–5" |
Both are approved on a rim 4" to 5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 145/65R17. Fit 135/65R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.4 mph | -0.6 |
| 50 mph | 49.0 mph | -1.0 |
| 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 9,790 on the road, so it over-counts by 210. At a true 70 mph the first turns 963 times a minute, the second 984.