ive used these before, and they are pretty nice,and cheap!
http://www.motosport.com/atv/product/KENDA-SAND-GECKO-REAR-TIRE-18x9x8/?catalogId=103677&refine=1&sBrand=Kenda&srchHistoryURL=fa2sg3jq||parentCategoryID~264^superParentCategoryID~category_root^parentCategoryName~ATV^categoryID~265^categoryName~ATV%20Parts@hz90csho||parentCategoryID~265^categoryID~278^categoryName~Tire%20and%20Wheel@lbc8msxf||refineType~1^sub_attr_name~Brand^refineValue~Kenda