Nomex Underwear for Protective Racing Clothing

Why Racers Wear Nomex Underwear Under a Fire Suit

You wear Nomex underwear because it adds protection time your suit can't provide alone. SFI recommends FR underwear with every driver suit, and it roughly doubles minimum protection time, adding about 3 seconds.

That extra layer matters most with a single-layer suit. An SFI 3.2A/1 suit has a TPP rating of 6, which works out to about 3 seconds before a second-degree burn. An SFI 3.2A/5 suit has a TPP of 20, or about 10 seconds. Those extra seconds count when you're unbuckling belts and climbing out of the car.

If you run a single-layer suit, underwear is the simplest way to close that gap. Browse racing suits to check your suit's rating, then build out the rest of your racing safety equipment around it. Impact Racing offers a long-sleeve Nomex undershirt and Nomex underpants. Always check your sanctioning body's rulebook before you buy.

What SFI 3.3 Means for Fire Retardant Underwear

SFI 3.3 is the spec that covers driver accessories, including underwear. It also covers hoods, socks, racing gloves, and driving shoes.

Under SFI 3.3, underwear, hoods, and socks need a minimum TPP of 6. TPP stands for Thermal Protective Performance, and a higher number means more time before a burn. SFI specs also fail materials that melt or drip, which is why the rating carries weight at tech inspection.

When you shop, use the SFI Rating filter to narrow results to certified pieces. Allstar Performance makes SFI 3.3 FR underwear tops and bottoms in black, sized SML through 5XL. Zamp Racing offers an SFI 3.3 underwear bottom. If your rulebook calls for SFI 3.3 accessories, look for the rating on the product page before you order. That way, you won't get surprised at the tech shed.

Types of Racing Underwear and Accessories

Racing underwear covers more than a shirt and pants. Here's what you'll find in this category:

• Long-sleeve tops, including the Sparco Shield RW-9 undershirt
• Bottoms and underpants that cover your legs under the suit
• Nomex socks from RJS Racing Equipment and SFI 3.3 socks from Impact Racing
• An SFI 3.3 fire-retardant sports bra from Zamp Racing
• The Impact Racing Transition balaclava, also called a head sock

Crow Safety Gear makes FR underwear tops and bottoms rated to SFI 3.3, with black among the color options. Use the Part Type filter to jump straight to tops, bottoms, socks, or head protection. You can mix pieces from different brands to build a full base layer under your suit.

Your balaclava sits under your helmet, so make sure both work together. Review race helmet requirements and ratings before you finalize your head protection.

Fire Resistant vs. Fire Retardant Underwear Materials

Fire-resistant fabric resists ignition by nature, while fire-retardant fabric is chemically treated to slow burning. Both terms show up on racing underwear, so it helps to know the difference.

Nomex is an inherently flame-resistant aramid fiber. Its protection comes from the fiber itself, not from a coating. CarbonX is another inherently FR fabric. Simpson uses it in a CarbonX long-sleeve underwear shirt, which you'll find in the parent driving suits and clothing category.

Fire-retardant fabrics start as standard material and get a chemical treatment. Proban-treated cotton is a common example. When you compare options, the Material filter lets you sort by fabric type. Check the SFI rating too, since certification tells you the piece passed testing regardless of how it gets its protection. If you're choosing between Nomex and CarbonX, focus on the rating, the fit, and how the fabric feels against your skin during a long run.

How to Size and Care for Fireproof Underwear

Pick your size from the Size filter, then keep the fabric clean so it protects the way it was tested. Sizes in this category run from X-Small to 5XL, so you can match tops and bottoms to your build.

Care matters as much as fit. Fuel, oil, and grease can soak into your suit and underwear, and those fluids can support flames. Keep your gear clean of those fluids, and store it away from spills in the pits and trailer.

If your underwear has been involved in a fire, replace it. The same goes for any other piece of gear that saw flame. For replacement timelines on other certified gear, read the SFI-rated parts replacement and recertification guide. Keep your underwear in a clean gear bag between events so it's ready when you are.