265/75R17 vs 245/85R17
Going from one to the other changes the overall height by +2.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 265/75R17 | 245/85R17 | Change |
|---|---|---|---|
| Overall height | 32.6" | 33.4" | +2.3 % |
| Sidewall | 7.82" | 8.20" | +4.8 % |
| Section width | 265 mm | 245 mm | -7.5 % |
| Circumference | 102.6" | 104.9" | +2.3 % |
| Revs per mile | 618 | 604 | -2.3 % |
| Axle height | 16.32" | 16.70" | +9.5 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 265/75R17. Fit 245/85R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.7 mph | +0.7 |
| 50 mph | 51.1 mph | +1.1 |
| 70 mph | 71.6 mph | +1.6 |
| 90 mph | 92.1 mph | +2.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,229 on the road, so it under-counts by 229. At a true 70 mph the first turns 721 times a minute, the second 705.
What drivers reported
265/75R17 carries 5 complaints. Nobody has filed one naming 245/85R17.