I checked the tires and none of them are loose but the right front tire is definitely slightly out of round. It doesn't take much to cause them to shake and hop.
My wife took a bunch of pictures of the cars and the track with her smart phone and emailed them to us. If anyone knows how to post pictures from an email and wants to do it let me know and I'll email them to you to post. I tried but it didn't work for me, I'm a computer idiot.