Fire-Resistant Racing Underwear: What It Does and When You Need It

Fire protection for a driver works in layers. Underwear, suit, gloves and shoes, plus a balaclava and socks, each add time before heat reaches your skin, and they work best as a set. This series goes through them one layer at a time, starting with the one closest to your skin.

How Layers Protect You

Fire-resistant fabric doesn't stop heat. It slows it down. Each layer of fabric has to heat up before the next one does, and so does the thin layer of air trapped between them. The more layers and air gaps between the flame and your skin, the longer you have to get out.

Suits are rated on exactly that. Under the SFI 3.2A system used in North America, an entry-level single-layer suit rated SFI 3.2A/1 is good for about 3 seconds before a second-degree burn. A two-layer suit rated SFI 3.2A/5 is good for about 10.

Two things follow from that:

• The suit's rating is for the suit alone. It doesn't count anything you wear under it.
• Underwear adds a layer and an air gap. Under a single-layer suit, fire-resistant underwear roughly doubles that minimum protection time.

When the Rules Require It

It depends on your organiser and on the suit you wear, so read your own rulebook. Two common examples:

• SCCA requires a suit rated at least SFI 3.2A/1, and treats fire-resistant underwear as optional only with suits rated SFI 3.2A/5 or higher, or with an FIA label. In practice, a single-layer suit means underwear.
• FIA rules treat underwear as a homologated garment in its own right. Under the current FIA 8856-2018 standard, underwear is heat-tested for the first time. The old standard only set a fabric density.

Plenty of HPDE groups don't require a suit at all. If you do wear one, wear the underwear too. A single-layer suit over a cotton T-shirt gives you the suit's rating and nothing more.

What Not to Wear Under a Suit

• Synthetic everyday fabrics. Polyester, nylon and spandex, which covers most gym and compression wear, melt when they get hot and can stick to your skin. Keep them out of the car entirely.
• Cotton. It doesn't melt, but it isn't fire-resistant, and it holds sweat.

That leaves fabric made for the job: Nomex and other aramid knits, or fire-resistant viscose such as the Lenzing FR used in the Alpinestars Race v3.

The Comfort Side

Good racing underwear also deals with sweat. It wicks moisture away from your skin and stops the suit sticking to you, which you notice by the third session on a hot day. It also keeps sweat off the inside of the suit, so the suit needs washing less often.

Fit and Coverage

• Leave room for the air gap. Part of the protection comes from the air trapped between layers. A suit that's tight over your base layer squeezes that air out and lets heat through faster, so size the suit with the underwear on.
• Long sleeves and full-length legs. Short sleeves and shorts leave bare skin directly under the suit.
• Close the gaps. The top should overlap the bottoms so nothing opens at the waist when you lean forward. Sleeve cuffs go under your glove cuffs, and leg cuffs go under your socks.
• Think about the neck. A high or mock-turtleneck collar, like the one on the OMP First top, covers the gap where the suit collar meets the balaclava.

Labels to Look For

• FIA 8856-2018. This is the current FIA standard, marked with a gold hologram tag. Garments are good for 10 years from the date of manufacture. Garments certified to the older 8856-2000 standard are being phased out by 2029, so buy 8856-2018 when you buy new.
• SFI 3.3. This is the SFI standard for driver accessories: underwear, gloves, shoes, socks and head socks. Some pieces carry both labels. The Alpinestars Race v3, for example, is rated FIA 8856-2018 and SFI 3.3, which covers you under either kind of rulebook.

Socks and Balaclava: The Rest of the Base Layer

Socks and a balaclava do the same job as underwear, at your feet and head. SCCA requires fire-resistant socks for every driver. It requires a balaclava if you have a beard or mustache, and any hair that shows below the helmet has to be covered with fire-resistant material. Under FIA 8856-2018, socks and balaclavas have to meet the same 5-second heat-transfer minimum as underwear. Part 4 of this series covers socks in more detail alongside shoes.

Our Picks

Every piece below is FIA 8856-2018 rated. Tops and bottoms are sold separately, so you can mix sizes.

Alpinestars Race v3: rated for FIA and SFI

The Race v3 is made from Lenzing FR, a fire-resistant viscose that feels soft and breathes well. It was updated in 2024 with a more relaxed fit. Because it carries both FIA 8856-2018 and SFI 3.3, it's the easy choice if you run with more than one club. Sizes run from XS to XXL in black or white.

Sparco RW-7: slim fit, cooling treatment

The RW-7 is a soft, stretchy Nomex blend with Sparco's X-Cool treatment, which draws heat away from the skin. The top has seamless sides and raglan sleeves, so nothing rubs under the suit.

Sabelt UI-600: regular fit, up to 3XL

The UI-600 is Sabelt's top-of-range base layer, made in Italy. This is the regular-fit version, for drivers who don't want a compression feel, and the seamless construction stays comfortable through long stints. The top runs up to 3XL.

Sparco RW-11 Evo: the top of the range

Sparco designs the RW-11 Evo for Formula 1 drivers. It's ultra-light and seamless, with X-Cool silver treatment and anti-bacterial properties, which helps on long weekends.

OMP First: the entry point

If you're buying your first base layer, the OMP First top is 100% soft-knit Nomex with flat seams, full-length raglan sleeves and a mock-turtleneck collar that covers the neck gap.

Looking After It

Follow the care label. Most makers ask for a gentle wash without bleach or fabric softener. Replace underwear that has worn thin or developed holes, because a hole is a gap in the layer.

The Bottom Line

Underwear is one of the cheapest layers of fire protection you can add, and under a single-layer suit it roughly doubles your protection time. Wear long sleeves and full-length legs in a fabric made for the job, never synthetic gym wear, and look for an FIA 8856-2018 or SFI 3.3 label.

Related reading: What to Wear on Track for the full kit and what order to buy it in, and Fire Protection in Race Cars for extinguishers and suppression systems on the car side.