The first point is making a flat spot on a rubber tyre this is caused by leaving the weight of the bike on the same spot all the time ...remember bike tyres are quite soft not the same as most cars tyres and are generally quite a hard rubber but then again if you leave a car over a long time you might cause the same problem if you don't move ..... again the same with suspension if you don't move it your causing it to be compressed in the same position again not so good for the bike.... so best idea leave it so it not compressed on suspension or tyres ...so lift it off the ground ....simples !
