Sams's Club has Pirelli P4 all-seasons in 195/65/15, which is the correct size for the Sonic 15 inch stock wheels. You can get them T-rated with a 90k treadwear warranty or the softer H-rated with a 70k treadwear warranty. I have two sets of these - one of each. I recommend the H-rated. The T-rated are pretty hard for a 15 inch tire, and I think they are special order only.
I can sell you mine. When would you like them and do you have an offer in mind?
$200 if in good condition and you are within driving distance. I'm m no rush, my 17" set is in perfect condition and fine for local driving.
It's surprising how there is nothing on eBay. Are Sonics rare vehicles, relatively?