Why does my front tyre wear out on the side but not in the middle?

This is because the road has a camber for drainage.

In England or Australia, it’s the right-hand side of a motorcycle tyre that wears out first, in other countries it’s the left hand side.

This problem has got worse with a lot of modern dual compound tyres. Where the tyre meets the road invariably seems to be where the harder compound central belt meets the tyre’s softer shoulder. So you end up with a steep angle on the right-hand side of the front tyre where the soft shoulder has borne the brunt of the camber and worn far quicker than the centre.

It isn’t as visible or extreme on the rear tyre due to the wider, flatter profile.