put my 19.5s on today

My 2004 TCD has had front end work about 151K now have 161K. Just tierod ends. I had the 19.5's from 9/15/08 with 95K on clock...have 66K on tires, backs appear to be about 1/2 worn, fronts lots left..at about 142K I did a depth check and calc'd the projected mileage fronts 167K, backs 157K so right now the backs should have 91K left and fronts 101K...just eyeballing I'd say I'll get another 75-85 for backs and fronts 80-90K...that takes into account the bits of chipped tread edges and general appearance. So in that 66K if I had stayed with OEM I would be well into the second set of tires since I was getting about 40K per set keeping them rotated and all that...which I don't even bother with on the advice of the Les Schwaub folks for dually, just check pressure before any long trips and if truck has been sitting. Back to calculating the costs...so by the time I reach the time to buy new 19.5's I would have spent on four sets of oem size tires at least a $1125 a time for 6 tires, mounting balancing and warranttee that is $4500 and that is 300 to 500 more than the 19.5 wheels and tires. Plus I get a whole lot of peace of mind...no value can be put on that plus no worries keeping them rotated and checking constantly for cracks and tread separation...like I said PEACE OF MIND!!!