Swirling noise when your wheels spin:
When your bearings are worn and lack lubricant they will start making a swirling noise. you can oil them to reduce the noise.
Squeaking sounds when you lean on your board:
These usually come from the pivot cup, it squeaks when the hanger’s pivot rotates in the rubber cup. To fix this, take your hanger off and wax the pivot liberally.
Sometimes squeaking also comes from your bushings shifting as you lean. Again, just wax the hell out of them.
Clicking/creaking sounds when you lean on your board:
These usually come from the washer directly below the kingpin nut (but may also come from the washer on the baseplate). The hole of the washer is commonly slightly larger than the kingpin so when you lean it may shift from side to side and create this clicking sound, you may also be able to feel it with your feet, the leaning motion is not smooth.
If your washer has an abnormally large hole, you can get washers which have a smaller hole (such as LSP precision titanium washers) so it fits better.
But sometimes it can’t be perfect, and it may also depend on the size of the kingpin (there are slight variations between different manufacturers even though they are the same “size”)
Another fix is to wrap the kingpin threads with plumber’s white teflon tape or some other tape to make it thicker. However this is hard to fit as the nut has to screw onto the kingpin and only the washer should be packed by the tape.
Another way is to glue the washer to the kingpin nut so it doesn’t shift around.
Or you can just ignore it, usually after some time it will break itself in and stop shifting (I imagine the washer might dent slightly with the kingpin nut and it sort of holds them together.) or you will get used to the clicking.
Metallic rattling sound when you are rolling, especially over rough ground:
The most common cause of this is the road-side washer rattling freely. This is because when you put your weight on the board, you will compress the board-side bushing and create more space for the road-side bushing, which sometimes frees up enough space for the washer to rattle around. To fix this, just tighten the kingpin nut slightly.
Another cause of rattling will be your mounting hardware being loose. You should always tighten your hardware after some time because they will come loose once your trucks/hardware sink into the deck.
Finally, it may also come from the spacers between your bearings (if you are using spacers). To properly use spacers, you should have the axle nut tight so that the inner rings of your bearings and the spacers are held together tightly by the nut. Some people want to use spacers but find that their wheels do not spin as freely, so they will loosen the axle nut slightly. This then allows the spacer to rattle around on the axle, so either tighten the nut down or just remove the spacers if you aren’t going to.
Low pitched creaking sounds that seem to come from your wheels as you roll:
These sounds come from the bearing seats of your wheels, (not the bearings but the interface between your outer ring of your bearings and the core of your wheel.) Over time, some wheels have bearing seats that become loose (you can see this when the bearings freely pop in and out of the seats with no force), and the bearings are able to shift very slightly inside the wheel as you roll, and especially when you make a turn. This slight shifting of the outer ring of the bearing produces this noise, and I actually think it shifts on most wheels but they are silent most of the time and not an issue.
If your wheel is annoying you with this noise, all you need to do is clean off the outer ring of your bearings, and clean the core of your wheel, then wax both surfaces. Wax allows this slight shifting to happen silently.
Other rattling/creaking sounds when you roll, especially over rough ground:
If it is none of the others above, it is probably your deck. check for delaminations between the plys, sometimes there are small splits or splinters, more common with bamboo plys and the sound comes from these little pieces rattling as you ride over rough ground. To fix these, use a high quality wood glue or epoxy and clamp, or just break off the stray splits/splinters.
And Finally, its pretty rare for someone’s board to be completely quiet. if the noises bother you while you are skating, try going faster so that the only sound you hear is the wind blowing over your ears.