The newer interactive smart trainers make indoor training much more attractive, to the point that many people now prefer to ride their trainer year round for safety and convenience.  The only problem is that the more time you spend on the trainer the more it wears a flat spot on your rear tire, especially if the tension on the roller is set too tightly.  Note this only applies to wheel mounted trainers; not direct drive trainers which were designed with this in mind.  The work around is to purchase a trainer tire, a hard tire that is designed for use on the trainer only, and an inexpensive rear wheel and cassette.  Swapping out your rear wheel can be a pain and most people do not want to hassle with it; they just use their road wheel.

A car tire is mainly flat and a cars suspension is designed to keep the most tire (contact patch) in contact with the road.  However a motorcycle or bicycle tire must be rounded as a two wheeled vehicle needs to lean in order to corner.  The faster the corner the more the lean, which means a lot more of the tire is required than just the middle.  A flat spot is fine if the bike never leans but as soon as you do you now have an edge (much smaller contact patch) you are riding on.  This creates a tire that is dangerous when you least want it to be, in a corner.  Wet conditions make this situation even worse.  

If you run your thumb across you rear tire and feel and edge on the sides it has a flat spot.  The wider the flat spot is the more hazardous the tire can be.  If you have been spending a lot of time on the trainer this winter and are ready to hit the road it is very important that you check the tire for a flat spot.  It just may save you some road rash, or worse.