I have one MTB with IRC Metros and the other with Michelin Wild Grippers. I can not complain too much about the IRCs. They are light, can hold 100 pounds and have a very low rolling resistence. In several seasons and thousands of miles I have only had 6 or so flats. The problem is that these have all occured during the past couple of months and are becoming more frequent. In contrast, the Michelins are heavier, slightly higher rolling resistence, but are very thick skinned. I have ridden over total crap with these without a single flat. So only Michelins for me from here on out, other than the Nokian M&G's which I stick on the front during the winter months. Like the Michelin's, the Nokians have a thick carcass, so can take a wicked beating.