I've got a set of these for when the terrain in a little too tough for the my 8ight-B.
http://www3.towerhobbies.com/cgi-bin...&I=LXNPN6&P=ML
Almost 'Monster' size without being too big, as to not bottom out the shocks first. Although I used the full offset rims I think 1/2 would do fine... maybe better. (will also help to clear a truck body as well if you decide to mount one)