It looks like a "Side of the shed special"
In other words it sat next to the shed so whenever someone mowed the lawn it flung crap against the wheel and tire.
On a serious not as others have mentioned, if I have ANY doubt about a tire it does NOT get used. The slit could have been a fraction of that size and I wouldn't touch it. I have some tires at home that I got as new tires...that were too old to even think about using. Just because the tread is good doesn't mean the tire is still good either. Cracking doesn't always show up on an old tire until it's been through a few heat cycles.
Used tires are like used helmets, not worth it no matter how good the deal.