One thing that probably would be worth doing is mounting them (and otherwise giving them a good look) while you're still in any return window. Have heard of the occasional tire which runs substantially untrue even when properly seated on a true rim, and of course there could be various sorts of structural issues, too.

The whole "bought it, forgot about it, pulled it out six months later and discovered it was defective but was told it was too late" is a story that comes up from time to time in e-commerce reviews. Such refusals are probably illegal, but difficult to do much about for small ticket items.

And quality control does really vary - found a needed rare size tube suddenly available online early last year, ordered one, it had a pinched spot that bulged when it was inflated, sent it back and got two others of the same item (from different sellers just to be sure) and they seemed fine. Really glad I looked though - the suspect one held air but I really didn't want to ride it.;