In my opinion yes. Although my sponsor does wheel/tire changes for me for $20. So for me to just change my mind doesn't cost me too much.

Definitely get a 2nd set of wheels/tires if you plan on doing this more often. Also gives you a peace of mind that if you get a flat at the event you can get home by using the other tires.

My house is wheel/tire central: 3 sets of tires not mounted, 2 sets of wheels not mounted with tires, and 5 sets of wheels/tire combos.