Inspired on the "Pireli Angel ST down to the wires" thread:
I found myself in the same situation, the tire I thought would be able to do the trip wasn't! I like my Shinko 011, cheap to buy, they perform great (don't believe the internet BS, I've scraped hard parts with them, turned them blue, etc), so this was my third set of them. Thing is...
I had never really quite worn out a set! I had them on my XT660X motard, only rode that bike in the city and the tires looked almost new when I sold it. Then I had another set on my '10 Versys, sold it after only 4,000 miles on it and didn't do any trips on it, so the tire did look pretty good. When the time came to put on a new set of tires on my '14 I went with another set of Shinkos, but this time I'm not selling this bike.
Problem with the 011, as well as many other tires, is that there are no grooves in the middle. How do you know how much rubber is left in there? Well, I think I know how you can tell on the Shinkos. This is what I first noticed on my tire:
It looks like some spots of lighter colored rubber... But it is not. I thought those patches of lighter rubber had worn through the thread and that the cords were just under that.
Truth is, the lighter color rubber is in fact the regular thread rubber, what is happening is that a darker band of rubber is showing up. When I took that picture I was 330kms away from the city of Durango, MX. in a very small mining town, getting a tire there was impossible. I decided to ride it back, slowly, and if the tire blew just get a towtruck, which would be easier to do closer to the city.
So I divided the trip in three parts, the first 110kms were ridden at/under 40mph, and this is what the tire looked like:
In that picture the darker band of rubber is showing, no spots of lighter rubber and it is clearly noticeable how that darker rubber worn trhough the lighter thread rubber. As the tire was holding on, I kept riding the next 110kms but I increased the pace to 55mph, and this is how it looked like:
I was pissed off, all that worrying for nothing! Darker rubber is still there, not getting much worse. So I rode the last 110kms like I'd normally do, and this is how the tire looked like when I got to the hotel:
I was already in the city, went looking for a new tire, and examined closely the tire after it was dismounted:
Only two little spots where the darker rubber had worn through, but still no cords showing. So well, there it is, this tire does give plenty of warning before it goes out, and if you happen to find yourself in the same situation I did, which seems likely given the lack of grooves in the middle of the thread, you know it still has some life left.