265/45R20 vs 245/50R20
Going from one to the other changes the overall height by +0.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/45R20 | 245/50R20 | Change |
|---|---|---|---|
| Overall height | 29.4" | 29.6" | +0.9 % |
| Sidewall | 4.69" | 4.82" | +2.7 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 92.3" | 93.1" | +0.9 % |
| Revs per mile | 686 | 680 | -0.9 % |
| Axle height | 14.69" | 14.82" | +3.3 mm |
| Approved rim width | 7.5–9.5" | 7–9" | overlap 7.5–9" |
Both are approved on a rim 7.5" to 9" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 265/45R20. Fit 245/50R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.3 mph | +0.3 |
| 50 mph | 50.4 mph | +0.4 |
| 70 mph | 70.6 mph | +0.6 |
| 90 mph | 90.8 mph | +0.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,087 on the road, so it under-counts by 87. At a true 70 mph the first turns 801 times a minute, the second 794.
What drivers reported
Nobody has filed a complaint naming 265/45R20. 245/50R20 carries 5.