275/75R23 vs 295/70R23
Going from one to the other changes the overall height by +0.1 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/75R23 | 295/70R23 | Change |
|---|---|---|---|
| Overall height | 39.2" | 39.3" | +0.1 % |
| Sidewall | 8.12" | 8.13" | +0.1 % |
| Section width | 275 mm | 295 mm | +7.3 % |
| Circumference | 123.3" | 123.3" | +0.1 % |
| Revs per mile | 514 | 514 | -0.1 % |
| Axle height | 19.62" | 19.63" | +0.3 mm |
| Approved rim width | 7.5–10" | 8.5–11" | 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 275/75R23. Fit 295/70R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.0 mph | +0.0 |
| 50 mph | 50.0 mph | +0.0 |
| 70 mph | 70.0 mph | +0.0 |
| 90 mph | 90.0 mph | +0.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,005 on the road, so it under-counts by 5. At a true 70 mph the first turns 600 times a minute, the second 599.