295/35R18 vs 275/40R18
Going from one to the other changes the overall height by +2.0 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/35R18 | 275/40R18 | Change |
|---|---|---|---|
| Overall height | 26.1" | 26.7" | +2.0 % |
| Sidewall | 4.06" | 4.33" | +6.5 % |
| Section width | 295 mm | 275 mm | -6.8 % |
| Circumference | 82.1" | 83.8" | +2.0 % |
| Revs per mile | 772 | 756 | -2.0 % |
| Axle height | 13.06" | 13.33" | +6.8 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 295/35R18. Fit 275/40R18 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 | 91.8 mph | +1.8 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,203 on the road, so it under-counts by 203. At a true 70 mph the first turns 900 times a minute, the second 883.
What drivers reported
Nobody has filed a complaint naming 295/35R18. 275/40R18 carries 2.