The et street is a street slick, the street radial is a drag radial. Their probably is a life difference between the two. Also, with the et streets, and driving in the rain, its compareable to driving on ice. You also need tubes for the et streets. The et street radial is a street tire, with softer compound.
For ET Streets, pour some dish soap inside the tire before mounting it...rub it all over the inside of the tire. Mount it without tubes. This will help prevent the rubber from letting air pass through it. It's a natural rubber which is why it leaks air, but the soap helps to fill the pores and slows down leaking. The tubes add considerable weight to the tires. Just keep an eye on tire pressure and hit the gas station air stations when you need to.