Felt Bicycles designs its bicycles in compliance with standards set by the International Organization for Standardization (ISO) which call for a minimum of 4-6mm of clearance on either side of the tire. Those standards are set, in part, for safety reasons. Felt Bicycles recognizes that some riders may still want even wider tires for certain uses resulting in less clearance on each side of the tire, but they do so at their own risk. Keep in mind each tire maker’s proclaimed widths may vary, even when marked the same size. And, keep in mind that rim width also affects tire width.