265/60R20 vs 245/60R20
Going from one to the other changes the overall height by -2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/60R20 | 245/60R20 | Change |
|---|---|---|---|
| Overall height | 32.5" | 31.6" | -2.9 % |
| Sidewall | 6.26" | 5.79" | -7.5 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 102.2" | 99.2" | -2.9 % |
| Revs per mile | 620 | 639 | +2.9 % |
| Axle height | 16.26" | 15.79" | -12.0 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 265/60R20. Fit 245/60R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.1 mph | -0.9 |
| 50 mph | 48.5 mph | -1.5 |
| 70 mph | 68.0 mph | -2.0 |
| 90 mph | 87.4 mph | -2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,709 on the road, so it over-counts by 291. At a true 70 mph the first turns 724 times a minute, the second 745.
What drivers reported
265/60R20 carries 2 complaints. Nobody has filed one naming 245/60R20.