There is a humming noise coming from my tyres on a smooth road?
Possibly you haven’t rotated your tyres in a while, check the rear tyres. Run your hand around the edge of the tread, first in one direction, then the other (Note: Be careful not to injure yourself on debris or exposed steel belts on the tyre). You are looking for a “saw-tooth” wear pattern between the tread blocks. If the tread is smooth in one direction but jagged in the other direction, you may have found some of the noise. Try rotating the tyres.