Really? If I knew this, I would make Bill Gates my gardener.
But seriously, too many variables for anyone other that your own self to know. You just have to work you way up and hopefully stay behind the breaking point.
I don't even try to get close to that point. I have felt the rear tire "roll" a couple of times and that's as far as I have pushed it. By roll I mean travel sideways yet maintaining grip, much like a flat tire would. I'm sure this is due to being bias ply instead of a radial. Can someone else confirm or counter this?
Randy