Experts estimate that steel-belted radials are 75% less likely to experience a flat or blowout than older radial ply tires. Nonetheless, if glass is very sharp, it can cut into the rubber tread of the tire. If it penetrates to the steel belt, it can cause a wound that will allow dirt and moisture to accumulate. Eventually, corrosion and contamination will cause the belt to separate from the tread, ruining the tire.