Continental Grand Prix 4000 Tread Wear Indicators?

What exactly is/are the tread wear indicators on the Grand Prix 4000 (non chili compound)? I see markings but at what does that tell me about the tread wear and when the tire is bad? I put two of these tires on my bike and I have road them 1,300 miles. I have been well satisfied and have had no flats. After my ride today I looked at my tires as usual. I noticed the rear tire all of a sudden appears to be wearing out. The bottom tread appears to be wearing off of the tire. The front tire is fine. I do not think I road over anything as the front tire shows little signs of wear. I was expecting FAR more than 1,300 miles on these tires. I was just about to post a glowing report on this tire and this happens today. Anyone have input? Thanks.

Anyone have input to the tread wear indicators on the GP 4000? I have tried the Continental web site and others and they just say there are tread wear indicators but no description.

There are little holes molded into in the tread at various locations. When the holes are gone, your tread is gone.

Personally, I’ve taken my Conti 4000s down to the point wear the tread started to look visibly flat as opposed to the orginal rounded shape and had no problems.

My rear tire wears about twice as fast as the front. 1300 miles is a bit on the short side but not too much. These are high end tires and the nice soft sticky tread which is not too thick to keep the weight down means they will wear out pretty quick.

Thanks. The little holes are gone!! I thought that may be the tire wear indicators but they are so shallow!! I bought these as long wearing and puncher resistant. Well they have been puncher resistant but definately not long wearing. I got 2,000 miles out of tires less than half thier price. Got any ideas on long wearing/puncher resistant tires?