275/40R17 vs 265/45R17
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 | 275/40R17 | 265/45R17 | Change |
|---|---|---|---|
| Overall height | 25.7" | 26.4" | +2.8 % |
| Sidewall | 4.33" | 4.69" | +8.4 % |
| Section width | 275 mm | 265 mm | -3.6 % |
| Circumference | 80.6" | 82.9" | +2.8 % |
| Revs per mile | 786 | 764 | -2.8 % |
| Axle height | 12.83" | 13.19" | +9.3 mm |
| Approved rim width | 7.5–10" | 7.5–9.5" | overlap 7.5–9.5" |
Both are approved on a rim 7.5" to 9.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 275/40R17. Fit 265/45R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,284 on the road, so it under-counts by 284. At a true 70 mph the first turns 917 times a minute, the second 892.
What drivers reported
275/40R17 carries 2 complaints. Nobody has filed one naming 265/45R17.