265/50R17 vs 275/45R17
Going from one to the other changes the overall height by -2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/50R17 | 275/45R17 | Change |
|---|---|---|---|
| Overall height | 27.4" | 26.7" | -2.5 % |
| Sidewall | 5.22" | 4.87" | -6.6 % |
| Section width | 265 mm | 275 mm | +3.8 % |
| Circumference | 86.2" | 84.0" | -2.5 % |
| Revs per mile | 735 | 754 | +2.5 % |
| Axle height | 13.72" | 13.37" | -8.8 mm |
| Approved rim width | 7.5–9.5" | 7.5–10" | 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 265/50R17. Fit 275/45R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.2 mph | -0.8 |
| 50 mph | 48.7 mph | -1.3 |
| 70 mph | 68.2 mph | -1.8 |
| 90 mph | 87.7 mph | -2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,749 on the road, so it over-counts by 251. At a true 70 mph the first turns 858 times a minute, the second 880.