I have more than 1,600 miles on a set of Conti Speed Rides and the rear tire is showing some wear in the shallow file tread. Not bad at all. I'm surprised because the tread feels very soft, like it would wear out quicker. But the Speed Rides have held up well on mixed pavement (smooth and rough, chipseal and striated concrete) and gravel -- some rough, mostly groomed crushed limestone trails.
I wan't expecting much when I bought the pair for $20 on a one-day Amazon sale last fall. But the Speed Rides have over-delivered. I'd pay the usual $20-$25 each to replace 'em after this set finally wears out. Actually I'll probably just buy one later this year, move the front to the rear and put the new tire on the front.