295/70R17 vs 285/75R17
Going from one to the other changes the overall height by +1.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/70R17 | 285/75R17 | Change |
|---|---|---|---|
| Overall height | 33.3" | 33.8" | +1.7 % |
| Sidewall | 8.13" | 8.42" | +3.5 % |
| Section width | 295 mm | 285 mm | -3.4 % |
| Circumference | 104.5" | 106.3" | +1.7 % |
| Revs per mile | 606 | 596 | -1.7 % |
| Axle height | 16.63" | 16.92" | +7.3 mm |
| Approved rim width | 8.5–11" | 8–10.5" | overlap 8.5–10.5" |
Both are approved on a rim 8.5" to 10.5" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 295/70R17. Fit 285/75R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.2 mph | +1.2 |
| 90 mph | 91.5 mph | +1.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,172 on the road, so it under-counts by 172. At a true 70 mph the first turns 707 times a minute, the second 696.
What drivers reported
Nobody has filed a complaint naming 295/70R17. 285/75R17 carries 1.