First the causes, most common is driving on under-inflated tires,others are hitting some object, especially with under-inflated tires, over heating the tires common when under-inflated or by making panic stops, jack rabbit starts," burning rubber," fast turns so the tires squeal, over inflated tires ( especially if you hit a big rock or brick), a puncture that leads to more damage, or manufacturer's defect. Used to be tires were made with fabric belts on a bias, that is layered at an angle to the treads and criss -crossed. Now days most tires have steel wire belts ( making some tire swings very uncomfortable with their poking ends) the belts are layed radially, or at right angles to the tread, interlayered with some running around the tire in the same direction as the tread. The wire forms are painted with various "rubbery glues" and placed in a mold and the "rubber" is poured in forming the tire and cementing the belts together. If the tire is under-inflated the wires flex, twist, and bend too much and can break or the stress can cause the wires to pull loose from the glues and separate. Unless you got evidence of a maker's defect, the cause is driver abuse. If you continue to drive on under-inflated tires you will have to register with the state and get a bumper sticker " Tire Abuser."

Only adding to other answers. . .a poorly done retread could do it too. There was a case near where I live where a guy was only doing 60 MPH and the steel belting somehow separated from the rubber inside the tire (it was a retread). He. . .is er. . .no longer with us. According to the local paper, the investigation cited the poor quality of the retread job as the cause.