This one will probably be best (if you don't mind the tire tread been a little different) for your size.
http://www.rcbrmin.com/rubber-tires-...der-p-735.html
RC4wd has this that are about the right side in diameter but not as wide.
http://store.rc4wd.com/MIL-SPEC-ZXL-...es_p_1957.html