Foam Tires for RC Cars: Why Are They a Thing?

When I first got into RC cars, I assumed that RC tires were filled with air. But they’re not.

Most RC car tires have a foam insert in the tire that performs several vital functions.

Are the foam inserts critical to the performance of the tire and the car, or can you discard these inserts?

The foam inside RC car tires is there to help the soft rubber tire keep its shape when the tire is rotating and moving over the ground. Foam tires for RC cars simulates the air in pneumatic tires in real-life cars. Different foam inserts can be used depending on the driving needs of the RC car.

Foam inserts are an essential part of RC car tire structure, and the tires should never be run without these inserts.

Why do RC car tires need these inserts, and are there other options to improve tire performance? We have the information to answer these questions and more in our discussion on RC tires!

What Is The Purpose Of Foam In RC Tires?

RC car tires are made from a relatively soft rubber compound to make them easy to purchase and use for RC enthusiasts.

The soft rubber compounds do not maintain their shape on their own, which requires an internal structure to overcome this issue.

That’s where foam tires come in.

But if real cars use air pressure to maintain the tire’s shape on the rim, why can’t RC cars use air pressure?

Real car tires have steel belts built into the rubber, which helps the tire maintain its shape when the wheel rotates, goes around obstacles, or over rough ground. The rims create an airtight seal with the tire to hold the air pressure.

RC tires don’t use the same technology as real cars to use pneumatic pressure. It would increase the cost of the tires, rims and the difficulty of replacing tires and wheels on RC cars.

Some high-end RC car tires are belted, with a support structure embedded in the rubber. This prevents the tires from ballooning rather than allowing the tires to be pressurized with air.

We have another article, “Why Do RC Tires Balloon,” which takes a more comprehensive look at this issue on RC car tires.

Foam inserts are the simplest, most cost-effective way for RC car tires to retain their shape and support the car’s weight while driving and negotiating obstacles in the terrain.

Blown tire with foam insert showing

What Are RC Tire Foam Inserts Made From?

There are varying substances that the foam is made from, each type giving different levels of support to the RC car tire.

Generally speaking, the foam is made from neoprene, similar to the substance in scuba diving wetsuits. It is a firm, compressible foam that can be made to different thicknesses and densities.

Thicker, dense foam will support the tire more rigidly, retaining its shape in more demanding conditions or rough terrain.

Higher density foam will improve the absorption of shocks from hitting obstacles on the ground or landing the car after big ramp jumps.

Are There Different Types Of Foam Inserts For RC Car Tires?

There are three main types of foam inserts for RC tires

Each type is intended to offer different properties to the tire, depending on your preference and driving requirements.

The 3 main RC tire foam inserts are as follows:

  • Standard RC tire foam inserts
  • Dual-stage RC tire foam inserts
  • Molded RC tire foam inserts

Standard RC Tire Foam Inserts

These foam inserts are the generic basic foam inserts that come standard with most RC tires. These inserts offer the basic needs to help the tire retain much of its shape but contribute nothing to enhance the performance of the tire or the car.

While these inserts will work for entry-level RC car driving, most advanced drivers will probably invest in more advanced foam inserts to improve the tires’ performance and increase the car’s handling capabilities.

When you start modifying your car, upgrade from a brushed to a brushless motor, or take it on more challenging terrain, you will probably need to use a higher-grade foam insert in the tires.

Some RC car operators trim the standard inserts to improve performance, but this must be done carefully. If the foam is cut incorrectly, it can result in an imbalance in the tire which can cause more problems than benefits.

Standard foam inserts can be fragile, so take care not to rip or damage the inserts when changing out tires. Damaging the insert in this way can also result in an unbalanced tire.

Dual-Stage RC Tire Foam Inserts

As the name implies, dual-stage foam inserts have two different layers of foam in their construction.

There is an outer layer made of less dense foam, allowing the outer part of the tire to flex, and an inner layer of denser foam against the wheel rim.

The inner layer of denser foam gives more rigidity against the wheel rim. This lets the tire absorb higher impacts, such as landing after large jumps, without the tire bottoming out against the rim and potentially damaging the tire.

Dual-stage RC tire foam inserts are more expensive than standard foam inserts. Still, they offer a significant improvement in the tire’s performance.

Molded RC Tire Foam Inserts

Molded RC tire foam inserts are the most expensive inserts for RC car tires.

The manufacturing process is more intensive, and a higher quality foam is used. The molded inserts are also made to fit specific rim sizes, meaning they are not a one-size-fits-all option.

Molded inserts fit snugly around the rim and fill the entire air space between the rim and the tire. Molded insets also have a rounded outer face, which provides pressure against the inner side of the tread part of the tire.

This more closely mimics the support given in full-size car tires by the air pressure contained in the tire. These molded inserts provide maximum support for the tire and increase the RC car’s road handling, cornering, and overall performance, even on rough terrain and hard landings.

Foam inserts in RC car tires are not an optional extra.

Foam pieces are integral to the tire structure and impact the car’s overall driving performance.

Once RC car drivers become experienced and try to get enhanced performance from their cars, one of the first things they upgrade is the foam in the tires. This modification allows the car to upgrade other components, such as specialized suspensions and higher-powered motors!

Tim Wells

Tim Wells is the creator and driving force behind His passion for RC cars began when he caught a glimpse of a Kyosho Optima while on a family trip to Japan. Although he couldn't afford it then, the seed of his RC car hobby had been planted, and he knew he had to have one. Fast forward a few years, and he could finally dive head-first into the hobby as an adult. He found a ton of websites and YouTubers doing crazy stunts with their expensive RC cars but very few resources for the average person who just wants to go out and have fun. That's when he launched his RC car website: ClutchRC.

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