275/55R18 vs 295/55R18
Going from one to the other changes the overall height by +2.9 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/55R18 | 295/55R18 | Change |
|---|---|---|---|
| Overall height | 29.9" | 30.8" | +2.9 % |
| Sidewall | 5.95" | 6.39" | +7.3 % |
| Section width | 275 mm | 295 mm | +7.3 % |
| Circumference | 94.0" | 96.7" | +2.9 % |
| Revs per mile | 674 | 655 | -2.9 % |
| Axle height | 14.95" | 15.39" | +11.0 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 275/55R18. Fit 295/55R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 72.0 mph | +2.0 |
| 90 mph | 92.6 mph | +2.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,290 on the road, so it under-counts by 290. At a true 70 mph the first turns 787 times a minute, the second 765.