I found some that were 7" wide. As Wolfen said, you can find them on Dodge vans, but I got mine from a LeBaron M-body.
I am using Hankook Optimo H724 Tires in the P235/75R15 size. They have a 3/4" whitewall and are $67.50 at Walmart (I had them shipped to a local store and installed by my...