considering that a bike is much lighter in weight.
motorcycle tires use a softer compound which wears a lot faster compared to the harder compunds on cars and of course the shape of the tire has something to do with it as well. motorcyles need these softer compounds so that it grips the road at higher speeds because of the lack of weight.
Simple fact that a motorbike has 2 tyres, hence twice the wear in a sense, since the car distributes its weight on 4 tyres. Also bikers tend to go slightly crazy on their bikes, even on the road, over taking, going faster than they should and so on, adding to the eventual wear. To insure that you get the most out of the tyre before spending another ?30 - ?100 on a single tyre, always have the PSI in the tyre at a correct level. If your riding around on low pressure, then wear will increase dramatically
Tires designed for longevity or high mileage are usually made of harder, longer wearing rubber compounds. This can be done because cars are more stable with four or more contact patches. Also, those contact patches stay fairly uniform in size due to the type of driving most people do. Performance car tires have poor longevity as well. Motorcycles usually use a stickier compound because the contact patch is smaller and subject to different forces than a car tire. Think about a bike in a corner, you're leaned over and there is little weight acting straight down like in a car but it is directed out towards the outside of the curve. There are longer wearing compounds but they are designed for the big tourers which do a lot of highway miles and are usually ridden in a more sedate manner.
