It seems that a lot of commonly held beliefs in 'cross just don't hold up (i.e., deeper dish rims are better in sand) or in bicycling in general (higher pressures = less rolling resistance). Which makes me wonder about tire tread. When a company comes out with a new tire, how much is this a thought experiment-turned-art, and how much is scientifically tested? And wouldn't we tire geeks want to know if scientifically tested, how such testing was carried out?
I wonder about this as some tires (like the new Specialized) are supposed to be great in the mud but their knobs are just as close together as others who are purported to clog up in the mud (Maxxis Locust for example). Do side knobs *really* help as much as we percieve? Hey, I've got questions!
I also came to this line of thinking after trying on the Vibram FiveFingers. A "slick" tread (for a shoe) that has AMAZING grip on a slick hardwood or wet rocks. Come to find out. it has little razor sipes that help it stick like glue. I know, it wouldnl't work so well as a 'cross tire but can you imagine a road slick that could stick like that?
I'm running a pair of blue Michelin Muds and they've got a cult status because they were using a compound that effectively made the tyres into glue. I was far more likely to start the grass tearing underneath me than actually have the tyres themselves lose grip. I've also run them at -20C, and they're about the best winter tyres I've ever had. You can turn pretty aggressively over packed snow at 25-30km/hr.
Muds are a great tyre because you could pretty much always win on them. Even if they weren't as amazing when the course was flat and dry, you couldn't really claim they were the thing holding you back.
I've got a set of Mud IIs waiting to go on my bike once the season actually starts—these old blue ones are training and winter tyres now (though I may run them as semi-slicks as the centre tread wears down). I haven't tried the IIs, but I've heard they're not quite as good.
As for the other stuff, I think there's a grain of truth to a lot of it, which is why people latch on. For instance, grip is influenced ONLY by the interface of the two materials...in an ideal situation. So a piece of rubber that's 1cm wide exerts the same grip force per unit area as the same type of rubber 5cm wide. The reason why we use treads and modulate the pressure is to ensure that the maximum amount of rubber is contacting the ground at any given time. A tyre with mud on it that won't shed grips only as well as the mud.
Similarly with tyre pressure. I think in an idealized model, you'd want the tyre pressure to basically be infinite. The reason why that doesn't work as well in the real world is because the force of impact will deflect the wheel and the bike, and slows the rider down, whereas a casing that flexes absorbs that impact. If the tyre could somehow project a field in front of it that swept all the bits of detritus off the road and filled all the potholes, you'd want to pump up the tyres because you'd want to reduce the amount of flex in the tyres when you pedal and MINIMIZE the contact patch with the ground. The ideal wheel is 1 atom wide, doesn't flex, grips infinitely, and isn't affected by debris. Hardly practical or possible.
So yeah, I'm sure there's science and art both going into the design of tyres, but science is a process of trial and failure. A few iterations of bad tyres is bound to happen to just about everyone, and it's impossible to test all the scenarios. They'll send out new tyres with sponsored riders, but amateurs are probably much harder on them, bizarrely, since they're more likely to use them badly and beyond the originally conceived specification.
Good choice on the five-fingers, BTW. I've got a couple pairs, and they're the best thing for your feet after a hard race.
Everything in modern media is overhyped not just in bike racing. For cross tires I have seen people that love a certain tire then have a bad race and the tire becomes the worst tire ever. Tires can and will make a difference, but can easily be overshadowed by tire pressure and rider ability. In my experience an afternoon of one on one time with a local instructor improved my cornering and handling more any set of tires. At the same time I have a few wheelsets that I can so I can run tires appropriate to the conditions...