Heavy Duty bicycle tires. Heavy duty bicycle tires are ones that have fortified casings and durable tread. Tires in this class will have enhanced weight load capacities. Heavy-duty tires will usually weigh 800 g or more and are found in just about every diameter. Different technologies may be in use in the same tire and some other technology include radial bias ply, Kevlar puncture protection belts and silica in the rubber. Heavy-duty tires are usually not cheap because all of the extra material it takes to construct them. The upside is the added safety and security.