I just got new tires and brakes put on my 2007 G6 base a few days ago and now I'm worried I got the wrong tires. I trusted my dad to get my car taken care of and I wasn't there to handle the transaction. They put on Kenda Kenetica 225/50R17's which I've never heard of before and so far they are ok but my gas milage is going down. Is this tire compatable for a pontiac G6? And I'm unable to find out any specs on them either. Any help is appreciated!