It really depends on the skill of the retreader.... obviously it is never going to be the same as a brand new tyre as you just don't know if the casing has fractured a bit or not........ the average retreader I guess would not have adequate equipment to possibly test the "unseen" condition of a bad casing.

HOWEVER................ you guys would be amazed at the percentage of commerical aircraft that use retreaded tyres. It is very very high!