when you say Z71 i take it to be a brand new one seeing they just started that packed again or due you mean the classic body style,if so a 265-75R16 will go on with out doing any thing to the truck but the 285-75R16 looks better but in order to make so they don't rub you'll have to push up the T/Bars,and if you have a brand new gm truck i would have to know what size oem wheel you have before i say what size tire you could run..