Join Date: Nov 2006
Location: San Antonio, TX
Z85 alloys are 6.5"
Z71 alloys are 7"
you can find out what tires will fit by those numbers. each tire has a recommended rim width range.
and the width wont effect the speedo, just the height. If you want it done, someone with hptuners or the dealer can do it for you.
2006 Black RC Z85 I4 M5
2008 Carbon Black Metallic Ext Cab Z85 Canyon 3.7L
2008 RC Sierra Black 4.8L