There is no fixed replacement interval that suits every skater. Dust, moisture, installation, maintenance and how often you ride all affect bearing condition. Inspect how the wheel turns rather than relying only on age or noise.
Signs to investigate
Check a bearing that feels rough, sticks, grinds under normal rotation, shows significant rust or has visible damage. First rule out wheel contact, incorrect assembly and excessive axle pressure. If the issue remains, cleaning may help a dirty but otherwise sound bearing.
When replacement is the safer choice
If the bearing remains rough or binds after appropriate cleaning and lubrication, or if it is cracked, badly corroded or otherwise damaged, stop riding it and replace it. Do not try to make a damaged bearing usable by adding more lubricant.
Replace the right quantity
Compare pack count with the number of bearing positions you need to fill. A standard four-wheel skateboard commonly uses eight individual bearings. Keep any usable spare bearings clean, dry and labelled so you know what they are.
For care steps, see the DSCO maintenance guide. For a replacement set, check the current product listings.