305/50R20 vs 295/50R20
Going from one to the other changes the overall height by -1.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 305/50R20 | 295/50R20 | Change |
|---|---|---|---|
| Overall height | 32.0" | 31.6" | -1.2 % |
| Sidewall | 6.00" | 5.81" | -3.3 % |
| Section width | 305 mm | 295 mm | -3.3 % |
| Circumference | 100.6" | 99.3" | -1.2 % |
| Revs per mile | 630 | 638 | +1.2 % |
| Axle height | 16.00" | 15.81" | -5.0 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 305/50R20. Fit 295/50R20 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.6 mph | -0.4 |
| 50 mph | 49.4 mph | -0.6 |
| 70 mph | 69.1 mph | -0.9 |
| 90 mph | 88.9 mph | -1.1 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,877 on the road, so it over-counts by 123. At a true 70 mph the first turns 735 times a minute, the second 744.
What drivers reported
305/50R20 carries 4 complaints. Nobody has filed one naming 295/50R20.