new tires found on craigslist

These tires will be a little wider and taller, so you may have problems with them rubbing on the fenders. You definitely will need to replace all 4 if you chose this route. I would check in your owners manual or with Tire Rack http://bit.ly/gnHfS to be sure!

This tire calculator might help: http://www.discounttire.com/dtcs/infoTireMath.dos