9" stretch ruined my engine, how to prevent??

[Dodgeme]

pics of how you stretched it would be very helpful to determine if the stretch actually had any effect on it. I would look into getting the tire and wheel balanced as well especially when stretching, but I've bought pretty poorly balanced tires and there was a lot of vibration before I had them balanced, just something to look into/ think about.
Usually when you see a break like this if it stress cracked along a flaw you will see areas that almost look old or different or even crystallized along where the part failed the old/ dirty looking areas are usually where its been cracked for a while and on a few occasions I've even seen where the cracks weren't even visible prior to the failure but looked dirty, corroded, or discolored along the failure with a clean looking break in a few areas of the failure