So I'm surfing youtube when I happened upon this video. If you've ever chopped wood I think you'll agree, this is pretty ingenious...
That thing looks pretty cool, but I'll bet it costs a LOT more than an old tire. My ex FIL had a heart attack, and after he recovered the doc told him he needed to get more exercise. He had a tree dropped in his backyard, and he used to go out and chop wood for exercise. Seemed to work pretty good for him. I guess it comes down to what you have more of - time or money. And whether or not you need the exercise.