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What's Inside a Sentry Tire Solid Tire?

March 29, 2021

What’s Inside a Sentry Tire Solid Tire?

Sentry Tire chooses the 3-stage tire approach in the construction of our tires. The three basic layers are:

  • Hard Base Layer
  • Cushioning Fiber Layer
  • Wear-Resistant Rubber Layer

Much like an orchestra, each layer works in conjunction with the other to achieve the optimal balance between maximizing wear and durability.

The Hard Base Layer

The Hard Base Layer serves as the “binding” layer of a solid tire. The function of this layer is to ensure:

1. The tire base bonds tightly onto the wheel, so the wheel does not “spin” on the tire.
2. This layer also needs to be the hardest rubber layer because it needs to withstand the heavy force pushed on to the tire when the machine is running and carrying weight.

Sentry Tire’s hard base layer also has thin steel rods formed into a round band and “infused” into the rubber base. These steel rods are essential because they allow the tire to expand and retract when pushing in a wheel. The tire can “snap back” and bond to the wheel once it’s pushed in. The rods are comparable to a rubber band. If you pull on a rubber band, it expands, and you can push an object into the center. When you release the band, it snaps back to hold on to the item you wrapped it around.

Cushioning Fiber Layer

The cushioning fiber layer is essentially a “filler” layer that allows the solid tire to form its desired overall diameter. This layer makes up more than 60% of a traditional solid tire. Even though most of this layer is never used, the way this layer is manufactured is critically important to a solid tire’s structural integrity. If the right rubber compound is not used for this layer, it will not bond to the next layer and the green tire layer below it. The tire will start peeling and eventually fail and become unusable.

A common practice with other tire manufacturers is using old recycled rubber to fill in this layer. While this may be environmentally friendly, many different rubber compounds are fixed into this layer. This inconsistency dramatically reduces the accuracy of a tire’s curing temperature and time since each rubber compound has vastly different characteristics. Using recycled rubber might result in tire separation and reduce the tire’s maximum operating life.

Sentry Tire’s fiber layer is not sourced from recycled rubber; we utilize unused rubber left from the production of truck tires. We further enhanced our QC by testing various truck tire brands’ residual tire stock and picking the optimal rubber source that will bond to our own formulated rubber layers. Such consistency is essential to ensure there is zero variance when producing the final tire.

Wear-Resistant Rubber Layer

The wear-resistant rubber layer is the “crème de la crème” portion of solid tires. Each manufacturer mixes their own compound for this layer to achieve what they think is the right balance. Sentry Tire has many compounds for each type of application your machine might come across. Our standard compound has a mix of properties that will strike a balance between the following properties:

  • Cut Resistant
  • Wear Resistant
  • Heat Resistant

Each of these properties can be customized (or enhanced) based on the specific needs of the customer’s application.  Some additional rubber compounds available are:

  • Oil Resistant
  • Chemical Resistant
  • Static Free Compound
  • Low-Rolling Resistant
  • Low Heat Resistant
  • Extra Soft Compounds
  • Non-Marking Compounds

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