Title: Paddle tire

Content:
Paddle tires are mainly used on off road vehicles, specifically designed for use in sand and mud. They consist of a smooth tire core which has a series of large rubber cups (or paddles) attached to it. The volume inside of a paddle is much larger than the void of a knobby tire, so it is unlikely to clog up with sand/mud. A street legal mud tire is a more or less normal tire, but with extra large gaps or "voids" between each tread block (called "lugs") to allow centrifugal force to "self-clean" or fling the mud out of the gap. Smaller gaps trap the mud in between the tire lugs, which turns the tire into something resembling a "slick" with no tread at all, which will have no traction in mud. A paddle tire is an even more extreme version of this, optimized for mud or sand. The paddle provides superior traction in the sand, in part, because the paddles dig into the sand and push off from the buried sand, not just the surface, and in mud, the gigantic "voids" give no place for mud to stick. They work something like a paddle wheel on a paddle-steamer. Street legal mud tires are a compromise between large voids and a smooth rolling shape for on-road use. The more "extreme" a mud tire (such as a "Super Swamper") is, the harsher and louder it is on a hard surface. A "tractor tire" on a farm tractor is a somewhat more mild version of a paddle tire, only the voids are smaller to allow for limited use on hard surfaces, and the "lugs" are angled to give lateral traction. A paddle tire is so optimized for mud that the shape is of no use on anything other than a soft surface, since the vibration and lack of control of the tire would render a vehicle almost unusable. One other way the paddle tire is a specialized-application-only is that it gives only forward/rearward traction. This means that it is used on a wheel that drives a vehicle to push it forward, but gives little "lateral" (side-to-side) traction. For that reason, the tires of the vehicle that steer it are generally more "normal" tires, since a paddle tire on a steering wheel will just slide sideways rather than pulling the vehicle with it. So many 4WD vehicles will use paddle tires only on the rear, although the front wheels are powered as well. On a 2WD or a motorbike, the rear wheel is the only drive wheel, and so putting a paddle tire on the front wheels is useless or worse, since steering performance will be negatively impacted.

Title: Racing slick

Content:
A racing slick (also known as a "slick tyre") is a type of tyre that has a smooth tread used mostly in auto racing. The first production "slick tyre" was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tread, such tyres provide the largest possible contact patch to the road, and maximize traction for any given tyre dimension. Slick tyres are used on road or oval track racing, where steering and braking require maximum traction from each wheel, but are typically used on only the driven (powered) wheels in drag racing, where the only concern is maximum traction to put power to the ground.

Question: How do smaller gaps between tread cause a regular tire in the mud to resemble a slick tyre?
Answer: Smaller gaps trap the mud in between the tire lugs