Metzler ME880 Marathon rear 210/40-18
To me, and I aint no expert...it does look like a few miles have been put on it otherwise it would have the mold flash across the tire and the tiny nipples from the same.
Although this also looks to have a good amount of tread, for the price, even with free shipping, for $20-40 more you can have a brand new one.
Personally I would offer them $110 and free shipping or go buy a new one. Jus sayn.