245/35R20 vs 265/35R20
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 | 245/35R20 | 265/35R20 | Change |
|---|---|---|---|
| Overall height | 26.8" | 27.3" | +2.1 % |
| Sidewall | 3.38" | 3.65" | +8.2 % |
| Section width | 245 mm | 265 mm | +8.2 % |
| Circumference | 84.0" | 85.8" | +2.1 % |
| Revs per mile | 754 | 739 | -2.1 % |
| Axle height | 13.38" | 13.65" | +7.0 mm |
| Approved rim width | 7–9" | 7.5–9.5" | 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 245/35R20. Fit 265/35R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 51.0 mph | +1.0 |
| 70 mph | 71.4 mph | +1.4 |
| 90 mph | 91.9 mph | +1.9 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,206 on the road, so it under-counts by 206. At a true 70 mph the first turns 880 times a minute, the second 862.
What drivers reported
245/35R20 carries 6 complaints. Nobody has filed one naming 265/35R20.