The procore 275 650b set from schwalbe is a joint development with syntace that can be mounted to all conventional wheels with a minimum internal width of 23mm the system uses a new dual chamber system that allows you to run your tyres at extremely low pressures with out the risk of getting a snakebite puncture and has been in world cup races the dual chamber works by running the inner core with a high pressure of about 55 85 psi which progressively cushions very hard knocks the outer cham