Tire Construction

What is a tire made of?

There are three basic parts to a bicycle tire, the carcass, the bead core and the rubber tire tread. Furthermore, almost all SCHWALBE-tires have a puncture protection belt.

The carcass is a rubberized textile fabric, which is laid around the bead cores. The carcass is then coated with a rubber compound. The tire tread is applied and the whole assembly is vulcanized.

The bead core of the tire determines its diameter and ensures a secure fit on the rim. Generally the bead core of a tire is made of steel wire. In folding tires, the steel wire is replaced with a hoop of Kevlar fiber. The advantage is that the tire can be folded and that, depending on the size, its weight can be reduced by 50 to 90 g.

All SCHWALBE carcasses are made of nylon. The density of the carcass fabric is expressed in EPI or TPI (Ends Per Inch, Threads Per Inch). The range of carcasses used for SCHWALBE tires are 50, 67 and 120 EPI.

Generally, tires with denser fabric are more resistant to punctures and roll better. Yet the ultra-fine 120 EPI carcass is more susceptible because the individual filaments are very fine. The best compromise for low weight and resistance is around 50 to 67 EPI.

The rubber compound of a tire is composed of several components:

  • Natural and synthetic rubber
  • Fillers, e.g. carbon black, chalk, silica
  • Softeners, e.g. oils and greases
  • Anti-ageing agents (aromatic amines)
  • Vulcanizing aids, e.g. sulphur
  • Vulcanization accelerators; e.g. zinc oxide
  • Pigments and dyes

Depending on the compound, the composition is roughly 40 - 60 % rubber, 15 - 30 % fillers, with the other components accounting for the rest.

Almost all SCHWALBE tires have a puncture protection belt, though we purposely decided not to include them in the special light and sports tires. Even our standard tires are equipped with an effective puncture protection belt made of natural rubber. MARATHON-tires, with the proven combination of natural rubber and Kevlar fibers in the Kevlar®-MB-Belt ensures remarkably high puncture protection. Furthermore, our top of the range tires have highly efficient puncture protection systems which are specifically adapted to the particular requirements, for example Double-Defense® or SmartGuard®.

Which is the best puncture protection belt?

The current state of the art is our SmartGuard®, the safest puncture protection belt on the market. Other puncture protection systems like Double-Defense® or Kevlar®-MB-Belts provide a very high degree of puncture protection. The decisive advantage of the SmartGuard® is its effectiveness against objects that become embedded in the tread, that are rolled over at each turn of the wheel and will eventually perforate virtually any protection belt. When this happens, the thickness of the SmartGuard® proves its advantage as a drawing pin will simply remain stuck in the rubber without further harming the tire.

Which is the best rubber compound?

A rubber compound must satisfy various requirements that are to some extent contradictory: low rolling resistance, good slip resistance, low wear, longevity, solid lugs (MTB).

The conflicting aims of low rolling resistance and good wet grip always attract particular attention. Good grip implies that the tire must "absorb" a lot of energy while low rolling resistance requires a tire compound with low energy consumption. A good compromise can be achieved with a filling agent like Silica, but another solution is the use of several rubber compounds in one tire such as Dual Compound Technology.

We offer universal compounds that, as far as possible, combine all relevant features, as well as special compounds where one feature is particularly prominent. The MARATHON 23S compound of is one of our universal compounds, while on the other hand the Marathon XR 1A compound is used to achieve very high mileage performance. Another example is the Maximum Grip Compound of the STELVIO RAIN.