SOL
I dont think there is any tricks to taking tires off wheels without damaging the tires. thats if they were glued right the first time and there is no bead that is blown out. If you do get them off, you have to make sure you prep the tires real well or they will never stick together again without problems,even with using new rims, like they do when you mount a brand new set of wheels and tires... Im sure there are some tricks to doing this sucsefully but for the time and agrivation you will go through, the little bit off money will be WAYY worth it, trust me.
Hope that helps
Dan