295/30R17 vs 275/35R17
Going from one to the other changes the overall height by +2.5 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/30R17 | 275/35R17 | Change |
|---|---|---|---|
| Overall height | 24.0" | 24.6" | +2.5 % |
| Sidewall | 3.48" | 3.79" | +8.8 % |
| Section width | 295 mm | 275 mm | -6.8 % |
| Circumference | 75.3" | 77.2" | +2.5 % |
| Revs per mile | 841 | 821 | -2.5 % |
| Axle height | 11.98" | 12.29" | +7.8 mm |
| Approved rim width | 8.5–11" | 7.5–10" | overlap 8.5–10" |
Both are approved on a rim 8.5" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 295/30R17. Fit 275/35R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.3 mph | +1.3 |
| 70 mph | 71.8 mph | +1.8 |
| 90 mph | 92.3 mph | +2.3 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,255 on the road, so it under-counts by 255. At a true 70 mph the first turns 982 times a minute, the second 957.