What Is Silicone Rubber? A Cooper Tire Rubber Company Lesson from Rubber Feet and Rubber Stripping

There's a box of rubber feet on my desk right now. It's the replacement box, not the one that caused the problem, but every time I look at it I remember March 2024—the month I tried to save $1,240 and ended up wasting $3,120.

I'm a procurement coordinator, and I've ordered industrial rubber parts for about seven years. I've made mistakes before, but this one was special. It started with a simple question that I thought I already knew the answer to: what is silicone rubber?

Why We Needed Rubber Feet and Rubber Stripping

We build small electrical enclosures for commercial equipment. Each enclosure uses four rubber feet to isolate vibration and a strip of rubber stripping around the door to keep out dust and moisture. Nothing exotic. For years, we ordered through a distributor that carries Cooper Tire & Rubber Company products. The Cooper Tire logo on the packaging always made me think, “well, they make tires, so they must understand rubber.” That assumption was true, but I didn't appreciate why it mattered until I tried to replace them.

At the start of 2024, finance asked every department to cut purchase costs. I looked at our last order: 3,000 rubber feet and 200 feet of rubber stripping, for $2,980. Then a new online vendor quoted the same quantities for $1,740. Same black appearance. Same data sheet phrase: “silicone rubber.” I told myself rubber is rubber. I signed the PO.

What Is Silicone Rubber? What I Missed

Let's pause and answer the question I should have asked in January. What is silicone rubber? In plain terms, it's a synthetic elastomer with a silicon-oxygen backbone, and it is known for handling heat, cold, and weather better than many organic rubbers. That's why silicone rubber is used in seals, gaskets, and rubber foot pads for outdoor equipment.

But here's the part I didn't get: silicone rubber is not one formula. It's a family. One compound can be soft and flexible enough to seal a freezer door. Another can be hard, filled with extra plasticizer or recycled material, and fail after six weeks of normal use. The label “silicone” doesn't tell you shore hardness, compression set, tensile strength, or temperature range. I didn't know that. I also didn't ask.

In my defense, I was busy. In a bad move, I asked the supplier if the parts were silicone rubber, and they said yes. That was the entire technical review.

The Rubber Feet Looked Fine. That Was the Problem.

The parts arrived on time. The rubber feet were uniform, and the rubber stripping had smooth edges. One of our assemblers pressed a rubber foot with his thumb and said it felt softer than the old one. I said it didn't matter. It did.

Six weeks later, a customer reported that the door gasket on an enclosure had pulled away. The rubber stripping had shrunk. It was within length tolerance when we installed it, but after weeks of normal heat and a mild cleaning solution, it contracted and left gaps. The rubber feet were worse. When we removed a foot from one of the returned units, it had flattened. Not compressed slightly—flattened, with a permanent dent. The 65A hardness we thought we ordered was more like 35A once it warmed up.

I remember standing at the inspection table holding a $0.11 rubber foot that had just caused a $380 service call. We had 3,000 of those feet in stock.

Here is the part that still stings: the vendor's data sheet said “silicone rubber.” But when I pushed for details, they couldn't provide a material specification or a test report. The product was likely a silicone blend with too much filler, or maybe a different polymer altogether. I can't say for certain, because the vendor stopped answering emails. All I know is that it was not silicone rubber in the sense that any legitimate rubber company would define it.

Calling Cooper Tire Rubber Company for a Real Specification

Eventually, I called our distributor and asked for a rubber materials specialist. The person who replied had the Cooper Tire logo in her email signature, and she asked better questions than I had: What environment would the rubber feet and rubber stripping face? What loads? What temperature range? Did we need resistance to specific cleaners?

When the new quote arrived, it was $3,160—slightly more than the original $2,980, because we added a low-temperature requirement and a specified compression set. The rubber feet were specified as 65A shore hardness. The rubber stripping was required to survive 180°F and contact with industrial cleaners. The material data sheet came from Cooper Tire & Rubber Company's rubber group, not from a generic product page. There was even an ASTM D2000 line item, which is the kind of boring detail that prevents expensive surprises.

I know what you're thinking: this is a Cooper Tire ad. I get it. But the logo didn't fix anything. The specification did. The Cooper Tire Rubber Company name gave me a way to hold someone accountable, and that's what I paid for.

The Cost of Choosing Price Over Value

Let's do the math, because this is where “value over price” stops being a slogan.

• Budget vendor quote: $1,740
• Original Cooper Tire distributor quote: $2,980
• Apparent savings if I'd ordered right: $1,240
• Field rework for 34 enclosures: $2,300
• Rush shipping for replacement rubber stripping: $180
• Labor to inspect and quarantine the bad rubber feet: $640
• Total avoidable cost: $3,120

So I saved $1,240 on paper and created a $3,120 problem. Then I spent another $3,160 on the correct parts. In the end, fixing my “savings” cost more than twice what the original order would have cost. The cheapest rubber foot in the world is not cheap if it fails in two months.

The lowest quote is not the most expensive choice until you add rework, downtime, customer frustration, and the cost of explaining why you said “silicone rubber” without asking what that phrase actually meant.

What I Check Now Before Ordering Rubber Parts

I put a checklist on the wall next to my desk. It's not dramatic, but it would have saved me the worst three months of my procurement career.

1. Define the environment: temperature, chemicals, UV exposure, load, and expected life.
2. Ask for shore hardness and compression set. If the supplier doesn't know, that's a red flag.
3. Ask if “silicone rubber” is a pure compound or a filled/recycled blend.
4. Request a data sheet from the actual manufacturer, not just a distributor summary.
5. Order a sample batch and test it under real conditions before buying the full quantity.
6. Compare total cost, not unit price: installation, replacement rate, service calls, and reputation.

That last point changed how I buy everything. A rubber foot at $0.32 that lasts five years is cheaper than a $0.11 rubber foot that lasts two months. That's not a theory. That's the invoice on my desk.

And there is something satisfying about opening the replacement box now. The rubber feet feel right, the rubber stripping seals correctly, and eight months later, none of it has changed shape. It sounds ridiculous to celebrate rubber feet, but when you've replaced 34 enclosures because of a bad compound, boring reliability is a beautiful thing.

Bottom Line

What is silicone rubber? It's a family of materials with a wide range of performance, and a label alone isn't enough. The same is true for rubber feet and rubber stripping. The material name is only the starting point; the specification is the real contract.

I still order through the Cooper Tire & Rubber Company distribution channel. Not because of the Cooper Tire logo, and not out of loyalty. I order there because they gave me a material standard I could verify, and because the rubber foot under my desk has not changed in eight months.

If you buy industrial rubber parts, you don't need to be a chemist. You just need to know that the question “what is silicone rubber?” has more than one answer. And if you don't ask which answer you're getting, you will eventually pay to learn it.