Purchasing a wider tire for the rear actually won't get you that much more grip because extra 1.5 inches of tire really don't make that much of a difference overall. What you want to do is get another set of tires and get some sticky tires on it that you can use when you go to the track.

 

I never have gone to a track and don't plan on soon. I need a grippy tire I can use every day for while. I guess I cant really get what I need

 

Lay off the gas. The track is probably the safest place to drive like a bat out of hell.

 

If you want a grippy tire that you can run on the road you're going to sacrifice tread wear, you simply can't have both great grip and long life, it's not possible. Choose your poison, but the tire you (and everyone else for that matter) wants is made out of unobtanium.