Is this a good deal? '13 Ranger XP900 for 7k

All things being equal and not being able to see or hear it run across the internet, that's a pretty good price IMO if it's in good mechanical shape (which the pics lead to believe).

2 things of concern are 1) tractor style tires like that are used for mud bogging and 2) front fairlead mount on bumper destroyed, how/why ??

It looks like a reasonably well cared for machine. The fairlead mentioned above is worthy of a question, but in my opinion not a deal killer. I've only purchased used Rangers and have never had a serious issue. I do my own maintenance and follow the book, mostly. When buying, I do check all the electrical systems and switches to ensure everything electrical is working as it should. Look at the oil on the dipstick and listen for any tranny noises. I have the same year and model and have had no issues. Just a note, in my part of the world (North Florida and Southeast Georgia) the tires would not be significantly unusual. What I call the "real mudders" would have REALLY aggressive tires, snorkels, and likely the radiator relocated higher. To me, it all looks normal, but I only know what I personally call normal in my area. All the best with you decision.

Sounds like its a good deal for the seller -