hhmm.. well the balder a tire is.. the better traction it gets, so just get a ghetto tire that has hella holes in it and stick it on ur rear and keep the bald ones in ur front
although in the rain ur dead meat <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>