The same reason for why motorcycles or bicycles lean into turns. Roller coaster tracks are designed in such way that the ride always leans into the turns. Even NASCAR tracks are inclined on corners.

The wheels are 101 millimeters big and made out of urethane. Having big wheels allows it to go faster and easily over any terrain, giving it a smooth ride without compromising the ground clearance. It will get you around town a little faster. 

This longboard is lower to the ground which makes it perfect for cruising and carving purposes. It also gives you better handling and stability and gives you more confidence to make those quick sharp turns. The system of parallelogram linkage trucks move jointly at specific angles, Allowing the wheels to lean into the turns so you can make really quick carves. These trucks are spring loaded so you get a constant force. It's very consistent the whole time which makes it very responsive.

The lean trucks have the same screw hole location attachment as the regular standard trucks so it is easier to attach it to any other board. Also, the wheels have the exact same 8-millimeter bearings as the regular wheel bearings so you can use these wheels on your trucks if you like.