305/45R17 vs 295/50R17
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 | 305/45R17 | 295/50R17 | Change |
|---|---|---|---|
| Overall height | 27.8" | 28.6" | +2.9 % |
| Sidewall | 5.40" | 5.81" | +7.5 % |
| Section width | 305 mm | 295 mm | -3.3 % |
| Circumference | 87.4" | 89.9" | +2.9 % |
| Revs per mile | 725 | 705 | -2.9 % |
| Axle height | 13.90" | 14.31" | +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 305/45R17. Fit 295/50R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.9 mph | +0.9 |
| 50 mph | 51.5 mph | +1.5 |
| 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 846 times a minute, the second 822.