They are good because of the curve that facilitates air pressure regulation. That being said, if buying tires and letting them last a few years is your style, putting long distances on tires, wellies on them tear easily from movement, vibration, or even just time. If you regularly buy new tires and supports, they are excellent for use on the track or in racing. However, out of 20 cores I had 2 with bad cores and had to be reused or replaced with new cores.