Tires need to be balanced on initial mount,  maybe once a year as well to maximize tire life. Also, regularly rotated.    
Sears is too dang expensive,  Goodyear and Firestone not far behind;  best value is Costco or Sam's, and unless you are doing some crazy street racing or offroading there is no need for those ridiculously expensive fancy tires, don't get the super cheap ones made in china either.....    just the regular type tire.  You can order it online from Costco, they ship them here for free, takes a couple weeks, then you can setup and appt to get them installed.  
NEVER NEVER NEVER use tire foam fix-a-flat type stuff, not only will it ruin a tire, it will ruin the rim.  I've seen many many a rim and tire trashed.  If you did already better make sure your tire guy dismounts the tire from the rim and scrub both very well and get all that stuff off, even then might be too late.