What Race Car Drivers Wear Under Their Fire Suits

Race car drivers typically wear flame-resistant base layers—most commonly Nomex or similar aramid fabrics—under their fire suits: a long-sleeve top, long pants or briefs, knee-high socks, and a balaclava (head sock). Many also add FR-rated cooling shirts and in-ear communications. Sanctioning bodies generally require these layers to meet FIA 8856-2018 or SFI 3.3 standards, and they prohibit non-FR synthetics that can melt against the skin. Here’s how the ensemble works, why it’s required, and how it varies across series.

The Mandatory Fire-Resistant Base Layer

The “under-suit” is a critical thermal barrier designed to buy time in a fire, wick sweat, and reduce heat stress. Modern base layers use flame-resistant fibers such as Nomex, Kermel, or Lenzing FR blends, and must meet stringent motorsport standards (FIA 8856-2018 globally; SFI 3.3 in many North American series). These pieces are worn next to skin and under the outer multi-layer suit, gloves, and shoes.

• FR long-sleeve top: Close-fitting, seamed to minimize pressure points, rated to FIA 8856-2018 or SFI 3.3.
• FR long pants/briefs: Full-length bottoms or boxer-style briefs in the same certified fabric.
• FR socks: Knee-high to keep skin fully covered beneath the shoes; certification required.
• FR balaclava (head sock): Typically double-layer; helps protect scalp, face, and neck and interfaces with the helmet.
• FR undergarments for fit/comfort: Sports bras and underwear made from FR or natural fibers to avoid melt risk.

Together these layers significantly increase thermal protection performance (TPP) and reduce the chance of burns from heat and hot gases that can bypass zippers, cuffs, and collar areas.

What Not to Wear

Certain everyday athletic garments can be hazardous in a fire. Series and scrutineers increasingly enforce bans on non-compliant layers, after incidents showed how quickly synthetics can melt or drip onto skin. FIA officials, for example, tightened checks in 2022 on FR underwear compliance across top series.

• Non-FR synthetics: Polyester, nylon, elastane compression gear, and standard “dry-fit” tees can melt and adhere to skin.
• Unrated base layers: If it’s not FIA 8856-2018 or SFI 3.3 (as applicable), it may not be allowed—even if it looks technical.
• Cotton as a substitute: Better than synthetics in a fire but not moisture-managing; many series still require certified FR layers.
• Jewelry and watches: Heat-conductive, snag hazards, and increasingly prohibited beneath suits.

The safest approach is to use only labeled, homologated FR garments designed for motorsport and to confirm requirements with event regulations.

Optional and Series-Dependent Extras

Beyond the core FR layers, drivers may tailor what they wear under the suit to cope with cockpit heat, hydration, and communications. What’s allowed can vary by series and scrutineering practice.

• FR cooling shirts: Garments with microtubes that circulate chilled water (e.g., “cool shirt” systems). Many teams use FR-rated versions or ensure non-FR components are fully covered.
• Hydration and comms integration: Balaclavas with drink-tube ports; in-ear radio earbuds that also function as hearing protection.
• Biometric sensors: Heart-rate straps or patches, temperature sensors, and crash sensors—worn under the base layer when permitted.
• Support gear: Knee or elbow braces, rib or kidney support in select disciplines, provided they don’t compromise fire protection.
• Urine management on long stints: Some endurance drivers use medical-style external catheters/collection systems; others simply plan pit stops—policies and preferences differ.

These add-ons can improve endurance and safety but must not undermine flame protection or violate homologation rules.

How Rules Vary by Sanctioning Body

Requirements are broadly similar, but details differ across organizations and series. Always check the current year’s handbook or supplementary regulations.

• FIA-governed series (e.g., F1, WEC, WRC): FR underwear, socks, and balaclava compliant with FIA 8856-2018 are mandatory; scrutineers regularly check labels.
• NASCAR and many U.S. series: SFI 3.3 FR underwear, socks, and head socks are required; outer suits typically SFI 3.2A/5 or higher.
• IMSA, IndyCar: Follow FIA or SFI equivalency; FR underwear and balaclava are standard requirements.
• Club racing/track days: Some clubs allow multi-layer suits without FR underwear, but best practice—and often current rules—favor wearing FR underwear regardless.
• Karting: CIK-FIA suits are abrasion-focused, not necessarily FR; top-tier karting may not require FR underwear, though many drivers still choose FR base layers.

If in doubt, wear certified FR underwear; it’s a low-cost, high-value protection that aligns with most scrutineering expectations worldwide.

Care and Wear Tips

Proper maintenance preserves fire protection and comfort—and helps you pass scrutineering.

• Wash per label, avoid fabric softeners and bleach; these can reduce FR performance.
• Air-dry or low-heat tumble; high heat can degrade fibers and elastic.
• Replace gear exposed to fire, heavy fuel/chemical contamination, or excessive wear.
• Ensure full coverage: Tuck sleeves into gloves and pants into socks; eliminate skin gaps.
• Carry spare sets in hot climates to start stints dry and reduce heat stress.

Routine inspection and correct fit ensure the base layer works as intended when it matters most.

Summary

Under their fire suits, race car drivers wear certified flame-resistant base layers: a long-sleeve top, long pants or briefs, knee-high socks, and a balaclava, often supplemented by FR cooling shirts and in-ear communications. These garments must meet FIA 8856-2018 or SFI 3.3 standards, and non-FR synthetics are prohibited due to melt risk. While optional items and nuances vary by series, the core principle is universal: full, certified coverage next to the skin dramatically improves protection and survivability in a fire.

What to wear under a racing firesuit?

• Fire-Resistant Underwear for Race Car Drivers. Fire-resistant underwear is the essential first layer of protection for every race car driver.
• Fire-Resistant Long-Sleeve Top (Undershirt)
• Fire-Resistant Long Pants (Underpants)
• Fire-Resistant Socks.

What do NASCAR drivers wear under their fire suits?

In the past, fire-resistant underwear, socks, and balaclavas/head socks were recommended, but not required. As of 2023, the updated NASCAR mandate states that all drivers must wear SFI or FIA-rated underwear, socks, and a helmet skirt or head sock under their fire suit and protective gear.

What do racing drivers wear under their suits?

Beneath the outer suit, every F1 driver wears a full complement of FIA-certified inner layers, including:

• • Fireproof undershirts and pants – For sweat management and flame protection.
• • Balaclava – To protect the head and neck.
• • FIA gloves – With grip-enhancing silicone zones and pre-curved fingers.

What do F1 drivers wear underneath the suit?

F1 drivers do wear cooling vests under their fire suits when the temperatures are very hot.