the cruiser rears seem to hold up to bigger tires just fine. and the big deal is bigger tires make the rocks seem smaller. i am still running cruiser axles in my rig and i havn't poped a birfield yet. knock on wood. but i run a auto and a 3 f but still on 38s. i have been pretty hard on it and so far so good. but i watch hitting it with the tires cranked left or right. i swear some people are just alergic to birfields. i have never poped one but i have friens that wheel with me and they do in all the time. mike