The only axle I broke on my ZUK is when I crawled up a rock wall on the pavement, my rear pass tire stuffed into the fender so tight it snapped the rear axle when I tried continue forward. Proper bumpstops would have prevented this from happening. They should hold up. I saw a guy running 37's this weekend, he didn't break a axle but he did shear off his hi-steer bolts though. It wasnt fun getting him out of the woods.