here's my take.
the tires are the only thing connecting you/your vehicle to the ground. i have no problem, whatsoever, spending money on tires to keep my family, my friends, and myself as safe as possible. in total, no matter how large of tires you get, you will really only have approximately an 8 1/2" x 11" (probably a little bigger) size piece of paper holding you to the ground, and that's counting all four tires.
a 275 width tire is on the very border of being too wide for a stock sized wheel. just an FYI.
again to the OP and anyone, really. your car/truck. do whatever you like.
used tires are just a bad decision. just sayin'.
on another side note, i paid $700 for a full set of brand new Michelins on my truck. definitely worth every single penny. a cheaper brand tire (i.e. many tires from the Bridgestone line) would've been less expensive and better than used tires, a hundred fold. then again, i put nothing but Michelin or BFG on any of my vehicles. that's just me, and i've been through A LOT of tires.