Bicycles are rear-wheel drive, but road bike tires have the basic job of reducing rolling resistance against asphalt, so the tread blocks aren't particularly tall. When it comes to tire patterns, it's basically just grooves carved into the tread. At that level, tire performance depends more on the compound (rubber material) than the pattern, which is why many manufacturers produce slick tires with no pattern at all. But cyclocross is a different story.
↑As usual, the right side is the direction of travel.
This is a Panaracer CG that I'm running on the front wheel, and while there's a faint front-to-back distinction, if I mounted it backwards the pattern would barely change (though of course I use it the proper way).
↑This one on the rear wheel is a Challenge Grifo, and normally you'd mount it so the right side of the photo is the direction of travel.
When you zoom in on the contact patch...
You get this.
This direction cuts through mud progressively, so basically you mount it this way. With road bike tires, the grooves are there for water evacuation performance, but the thinking is the same.
But with MTBs, in the case of these arrow-shaped knob tires, you can sometimes mount the rear tire backwards. When you flip the rear tire, the blue line section I drew in the diagram above rolls along like a rake, clawing at the ground. That's the direction where traction—the tire's ability to transmit driving force to the ground—engages more effectively.
↑On a mountain bike, when several difficult conditions stack up—wet surfaces, leaf-covered ground, climbing—the crank rotation can suddenly slip out. More precisely, at the rear wheel's contact patch, the tire loses grip and slides instead of kicking the ground. Road bikes do this too when climbing on icy winter roads while standing out of the saddle. Setting up the tire for traction makes this less likely to happen, but with cyclocross you basically don't mount it backwards. That said, I do sometimes run it reversed.
With a road-style freehub, you can swap the tire's direction in about 10 seconds. Even if you remove the tire and flip it around as fast as possible and reinflate, you won't manage it in 10 seconds. So that's one way to tout the superiority of the freehub—and that's where this post punchline lands.
↑As usual, the right side is the direction of travel.
This is a Panaracer CG that I'm running on the front wheel, and while there's a faint front-to-back distinction, if I mounted it backwards the pattern would barely change (though of course I use it the proper way).
↑This one on the rear wheel is a Challenge Grifo, and normally you'd mount it so the right side of the photo is the direction of travel.
When you zoom in on the contact patch...
You get this.
This direction cuts through mud progressively, so basically you mount it this way. With road bike tires, the grooves are there for water evacuation performance, but the thinking is the same.
But with MTBs, in the case of these arrow-shaped knob tires, you can sometimes mount the rear tire backwards. When you flip the rear tire, the blue line section I drew in the diagram above rolls along like a rake, clawing at the ground. That's the direction where traction—the tire's ability to transmit driving force to the ground—engages more effectively.
↑On a mountain bike, when several difficult conditions stack up—wet surfaces, leaf-covered ground, climbing—the crank rotation can suddenly slip out. More precisely, at the rear wheel's contact patch, the tire loses grip and slides instead of kicking the ground. Road bikes do this too when climbing on icy winter roads while standing out of the saddle. Setting up the tire for traction makes this less likely to happen, but with cyclocross you basically don't mount it backwards. That said, I do sometimes run it reversed.
With a road-style freehub, you can swap the tire's direction in about 10 seconds. Even if you remove the tire and flip it around as fast as possible and reinflate, you won't manage it in 10 seconds. So that's one way to tout the superiority of the freehub—and that's where this post punchline lands.