Do motorbike tyres wear evenly, or does one side wear more quickly than another? Because motorbikes lean when cornering, and the tyre has a radius as opposed to being a relatively flat bottom like a car tyre, a motorbike tyre experiences varying levels of wear across the tread.
When the bike leans to the left, more wear is experienced on the left-hand side of the tyre and vice versa to the right.
However, due to the nature of our roads, one side of the tyre often gets slightly more worn than the other: the side of the tyre closest to the centre line.
This is because roads slope away from the centre line (the crown) and towards the edge of the road (the gutter), so that water can either drain into the drainage system or onto the verge to soak away or enter dykes.
This slope means that when the motorbike is upright, slightly more of the crown-side of the tyre (the right-hand side if you’re driving in the UK) is in contact with the road than the left-hand side. More force is exerted on this side of the tyre when accelerating or braking.
The second reason is due to the number of right-hand turns vs left hand turns, and the type of turns they are. Theoretically you would expect that there would be an equal number of right and left curves, but this isn’t the case, and the riding scenario is different.
Roundabouts form an artificially long right-hand bend compared to coming from the opposite direction turning left. The camber on a roundabout slopes towards the edge, meaning more of the right-hand side of the tyre is in contact with the road than would normally be the case on a regular road where camber is adjusted to be positive (i.e. the water drains to the apex of the corner).
There are other things that can cause increased wear or different wear patterns, such as poor setup of the bike, or riding with a sidecar, but the predominant wear pattern is created due to the camber of the road.