295/50R23 vs 305/45R23
Going from one to the other changes the overall height by -2.3 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 295/50R23 | 305/45R23 | Change |
|---|---|---|---|
| Overall height | 34.6" | 33.8" | -2.3 % |
| Sidewall | 5.81" | 5.40" | -6.9 % |
| Section width | 295 mm | 305 mm | +3.4 % |
| Circumference | 108.7" | 106.2" | -2.3 % |
| Revs per mile | 583 | 597 | +2.3 % |
| Axle height | 17.31" | 16.90" | -10.3 mm |
| Approved rim width | 8.5–11" | 8.5–11" | overlap 8.5–11" |
Both are approved on a rim 8.5" to 11" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 295/50R23. Fit 305/45R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.8 mph | -1.2 |
| 70 mph | 68.4 mph | -1.6 |
| 90 mph | 87.9 mph | -2.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,767 on the road, so it over-counts by 233. At a true 70 mph the first turns 680 times a minute, the second 696.