275/50R18 vs 295/50R18
Going from one to the other changes the overall height by +2.7 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 275/50R18 | 295/50R18 | Change |
|---|---|---|---|
| Overall height | 28.8" | 29.6" | +2.7 % |
| Sidewall | 5.41" | 5.81" | +7.3 % |
| Section width | 275 mm | 295 mm | +7.3 % |
| Circumference | 90.6" | 93.0" | +2.7 % |
| Revs per mile | 700 | 681 | -2.7 % |
| Axle height | 14.41" | 14.81" | +10.0 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 275/50R18. Fit 295/50R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.8 mph | +0.8 |
| 50 mph | 51.4 mph | +1.4 |
| 70 mph | 71.9 mph | +1.9 |
| 90 mph | 92.5 mph | +2.5 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,273 on the road, so it under-counts by 273. At a true 70 mph the first turns 816 times a minute, the second 795.