305/65R17 vs 315/60R17
Going from one to the other changes the overall height by -2.2 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 305/65R17 | 315/60R17 | Change |
|---|---|---|---|
| Overall height | 32.6" | 31.9" | -2.2 % |
| Sidewall | 7.81" | 7.44" | -4.7 % |
| Section width | 305 mm | 315 mm | +3.3 % |
| Circumference | 102.4" | 100.2" | -2.2 % |
| Revs per mile | 618 | 633 | +2.2 % |
| Axle height | 16.31" | 15.94" | -9.3 mm |
| Approved rim width | 8.5–11" | 8.5–11.5" | 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 305/65R17. Fit 315/60R17 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.3 mph | -0.7 |
| 50 mph | 48.9 mph | -1.1 |
| 70 mph | 68.4 mph | -1.6 |
| 90 mph | 88.0 mph | -2.0 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,777 on the road, so it over-counts by 223. At a true 70 mph the first turns 722 times a minute, the second 738.
What drivers reported
305/65R17 carries 3 complaints. Nobody has filed one naming 315/60R17.