I was told that all rubbers, including synthetics give of volatile substances continuously over time and degrade below safe levels of structural integrity. Now, if I only knew what that meant!!!
FWIW, After 22,000 miles the tread depth on my 17" Bridgestone Ecopia EP422 plus OEM tires is down to 8/32". I didn't measure them when new, but the published spec is 10/32" so they seem to have a lot of miles left In them.
I noticed the wear rating on the 17 inch Bridgestone's is much higher than the 15 inch variety of tires. The non-touring pre-eyes, got the cheap rubber.
There's a further wrinkle with the 15" EP422 plus, there's at least 2 variations (maybe a third, made in Japan variant): with different wear ratings, different countries of origin, and the even tread pattern varies: one has 3 widely space rows, the other 4 more tightly spaced.
That's amazing, don't even want to think what that is in kilometres. And 13 inch tires used to get you where you needed to go.
