biggest tire size

When I asked the question at Stockton Wheel, the answer I got was a 235/60-15 on a 7" rim with stock offset. There are guys on the site who swear you can get a 245/60-15 on the back. I tried a 255/60-15 at one point. It fit in the wheelwell but was only about a ¼" off of the rear spring. There are some other threads @ FABO that have discussed this topic before.