I had a problem with a pair of 20" Schwalbe Marathon Winter Studded tires that I have had on my Raleigh twenty for a couple of years.
ALL the center studs on the rear tire had pushed through to the inside of the tire and were causing flats. A couple on the front were starting to do the same.
You can see all the center studs now flush with the tire.
I had about 500 miles on them after three winters, at $70 plus bucks a tire, I thought this was a little short for them to wear out, especially in such a weird way. I emailed Schwalbe with the photos, they thought that I should submit a warranty claim, so I did a quick online form. They promptly emailed me that they considered the rear tire a warranty item and would be sending a replacement immediately.
Two days later I got a package with not one, but two new tires:
And a bonus christmas guardian angel ornament.
Pretty cool. That was some excellent prompt customer service. Thanks Schwalbe.
Now I have to overhaul the murderously grungy raleigh twenty and get it rolling again with fresh studded rubber.