While, as a modern motorcycle tire, I'm pretty high-tech, to the general public I'm just a black round things that wears out sooner than they'd like – and costs more than they want to pay. And that's the problem...
While I've evolved since the day I was created, I look pretty much the same as I did in the beginning. So, who can blame them for thinking we're all the same? It's on the inside that I've changed – so let's look. Strip away the kinky rubber clothing (which isn't much rubber anyway these days) and what you're left with is a fabric and steel skeleton. In fact, I'm pretty human in that sense. Your skeleton makes you move and feel the way you do and it's the same with my carcass.
Although the rubber has some influence, it isn't everything. A soft rubber on a stiff carcass won't grip as well as a hard rubber on a soft carcass.
There are several parts to my carcass, in the same way many bones make up the human skeleton. When you pick me up, the bit that you normally hold (which touches the rim), is called the bead. This is a hoop of rubber – covered metal strands that keep the tire on the rim. Just above that is what they call the bead-filler. This makes up the sidewall as such. If the bead-filler is flimsy, the sidewall is weak. Make it tough and you add strength to the sidewall and that affects how the tire feels to the rider.
The final part is arguably the most important, and is what we see if our tire wears to thin. It's also the bit you think of when we use the word carcass. It's the fabric material that gives the tire its shape and feel. Normally this starts life as a fabric, but isn't put into the tire like that.
Before then it's rubber-coated and cut at a precise angles so the 'grain' of the fabric can be laid at exact angles to each other. These angles are crucial to feel because they control how the carcass moves as it contacts the road and when they do move, these rubber-coated fibers rub slightly, and generate a little heat.
Labels like cross-ply and radial refer to the method of construction. The materials are the same for each type of tire - they're just put together differently. Most interesting of all is the fact that I’m not naturally air-tight. My inner lining is what keeps the air in. This butyl (Polyisobutylene) rubber is different from the rubber on the outside, although air can still permeate it, which is why you should check your pressures regularly.