jkrerol15 said:
...what's the best way for me to say for sure that it is worn out and just not safe. If I ask two people I get two different opinions on how much I've got left.
You'll probably get different opinions here, too.
Obviously, changing sooner rather than later is the best bet; but if you're trying to economize by only changing when absolutely needed, look for the "wear bars" that run across some of the grooves. If they're even with the surface of the tire, then it's time to change right away.
You can also measure the tread depth at several points, and if the average is below what the Owner's Manual recommends, then it's time to change. For the AN650 that's 1.5mm front and 2mm rear, I think. (I don't have my manual in front of me.) Measure at the centerline of the tire, and also midway between the centerline and the end of the grooves at the sidewall.
If you see cracks in the tire, or if the rubber looks "dried out" or "old," then it's time to change.
As Paul said, if you see obvious "out of round" sections, it's time.
Last, but not least, if you have to add air frequently ( a "slow leak"), then it's time.
HTH.