Not sure if you drive in the snow (your location is not filled in) but if you do be preparred for your rig to be very "tail" happy in the white stuff with a fresh set of front tires and old rears..... you will drifting that thing around like Jeremy Clarkson from Top Gear
I am also at the point of wanting to replace the stockers on our rig, it has a little over 35K miles and the tires have quite a bit of tread left (~60%) but they are getting a bit noisy and the rubber is getting harder, I noticed early this year in the snow and in the rain that the tires dont bite like they used to. Switching lanes in heavy snow after its grooved from other vehicles really pushes the truck around and has caused it to get a little loose in the tail which is not a big deal for me but with my wife driving I think I want fresh rubber on it before we get any signifigant snow fall here in the Chicagoland area.
One of my buddies has a 2006 as well but he has some bling bling wheels for the summer and puts his stockers on for winter..... the tires are like new (they probably only have 5-6K miles on them...... the truck itself only has 20K miles on it)..... I drove his truck in one of the last snows we had early this year and it was considerably better so I know my tires have lost quite a bit of grip. Just sucks to drop $1000+ for new rubber when they still got meat on them.