I found uneven wear of rear tire and had to check alignment. I actually did it twice. First time like FSM says checking distance between swing arm axle and rear wheel axle, second time I was aligning rear wheel by front wheel which I believe is better.
Who did alignment?

 

I would also think that aligning the front and rear wheels is the best way. What did you use as a straight edge? Did you use it on both sides of the bike?

 

It is better to do it like FSM says. I was wrong. If you align rear wheel by front wheel, belt will not be straight.