I have a set of 19.5" Michelin XRV tires with 70,000+ miles and about 1/2 the original tread still there.  
I also have a set of 19.5" Continental HDR tires with about 50,000 miles on them.
My 2008 truck has had the 19.5" Rickson eliminator wheels and tires since day one - swapped over from the 2004 truck I traded in.
I would not have anything else on my truck, but that's just me.