The GGs are different from the previous marathon hs368? I had a pair of lightly worn ones and also got one front and one rear visit in the space of a few miles. I still have those as well, but luckily the GGs seem to be excellent in that dept. When I fit my new set, it will interesting to keep a log on those as well, as visitations are based on luck as well as tyre construction. Once I had fitted some Specialized Nimbus Armadillos, for a hosteling trip in winter, @ Hathersage. Came out of the car park on first ride and pssst! I had run over an electricians cable clip, and of course these have small masonary nails. Luck really.