Vittoria Revolution G City Tire. Vittoria's new Revolution G City Tire sets a new standard of excellence for anyone who seeks a super durable yet super smooth rolling tire that delivers a plush ride on asphalt as well as well maintained dirt surfaces. This edition is designed for mountain bike wheels, with a version available for 26, 27.5 and 29 size options. There's plenty of technological wizardry taking place in these tires, too, particularly involving the use of Graphene. The Graphene in Vittoria's G Isotech tread compound is a nearly transparent sheet of pure carbon mere atoms thick. Prior to the development of Graphene, there was always the limitation of choosing between optimizing for speed, grip, durability and puncture protection. Effectively, the introduction of Graphene allows for natural material barriers of rubber to be removed, which means that there is no longer the need for such compromises between speed, grip, durability and puncture resistance. All these features now co exist in a single, Revolution G tire. Additionally, the Revolution G features Vittoria's 4 Compounds 4C technology which is a layering process that uses four separate compounds in the same tread. The 4C process offers unmatched versatility, by allowing for separate base and surface compounds in both the center and side areas of the tread. Benefiting from the different properties of each compound, including the G Isotech, their distribution has been extensively tested to deliver the best tire imaginable.