I just started to balance tires and pre-roll them in a Much more device, dedicated to clamp and turn the TC rubber tires (very similar to the ones used to trim the foam tires).
My experience confirm everythig that was written on this forum, but:
1 - If you are racing in BIG tracks with 3,5T brushless motors and high speeds it is worth to balance the tires.
2 - To balance the tires is only interesting if you get like 3 sets of equal tires and (if pre glued) make one set of them by choosing the 4 more balanced and then finally balance them to one acceptable level.
3 - If you can glue tires (even with the same components of the control/pre glued ones) , using 2 rubber rings by tire + weight previously the rims, tires and inserts to assure they weight each the same) they will be 90% balanced.
4 - Before balancing I allways put them in this "turning/spinning" machine and sand them with 200 0r 300 sand paperwith a flat block.
Purpose: A) to sructure the surface for better tire conditioner/additive in this so important first run - where everybody is on fresh tires
B) so "help" the tire getting trully round
C) to give the tire/insert a "shake down" before balancing.
thanks in advance for all the information / experience on this subject