If it ain't broke, don't fix it. That sums up the mentality of most replacement-tire buyers. But there are downsides to conventional all-season tires. Cold weather, for instance, can stiffen them so much that they struggle to keep their grip. And besides, specialty tires just make sense sometimes. A run-flat, for example, is a great insurance policy if you often travel through remote areas. And if you have a souped-up sports car, why not run it on the most responsive rubber you can buy? Here are the pros and cons of each of the four major tire types.

Chris Pesa is one of the first people to put the Segway Human Transporter (a.k.a. It, Ginger, and the Invention That Will Change the World) to a real-life test on his 390-stop mail route in Tampa, Florida. We caught up with him to see how it works.