A racing suit is cut to cover the entire body, with long sleeves and full-length legs. Most driver suits are one-piece overalls resembling a boilersuit, though two-piece jacket-and-trousers configurations also exist. Suits are constructed from one or more layers of fire-retardant fabric, and include reinforced epaulettes or yokes at the shoulders designed to act as handles for extracting a driver still strapped into a race seat — a feature mandated under FIA safety standards.
The dominant material is Nomex, a synthetic aramid fibre produced by DuPont and developed in the 1960s. When exposed to flame, Nomex does not burn or melt; instead it forms a thickening carbon char that slows heat transfer to the wearer. Other fabrics in use include Proban-treated cotton, Kevlar, polybenzimidazole fibre, carbon fibres, and CarbonX — an oxidised polyacrylonitrile material rated to two minutes of direct flame exposure. Proban-treated suits can lose their fire resistance over time, particularly after repeated washing, a limitation not shared by Nomex.
Suits are not fully fireproof but are designed to be fire-retardant for long enough to allow escape or rescue. Safety innovator Bill Simpson estimated in 1993 that a wearer typically has twenty to thirty seconds before the suit itself begins to burn. The NHRA sets a higher benchmark than most other series, requiring suits to provide thirty to forty seconds of protection before second-degree burns occur, reflecting the elevated fire risk from nitromethane-fuelled vehicles.
Two main bodies govern fire suit specifications. The SFI Foundation, formerly part of SEMA, sets standards for NASCAR, IndyCar, the NHRA, the SCCA, and the USAC, among others. The FIA sets standards for its own series, including Formula One and the FIA World Endurance Championship, but defers to SFI for its drag racing competitions. Both bodies use the Thermal Protective Performance (TPP) test, developed by DuPont in the 1970s, which measures in seconds the time before a wearer suffers second-degree burns. A garment scoring three seconds on the TPP test receives a value of six and an SFI rating of 3.2A/1, the lowest SFI classification.
Non-fire-retardant suits also exist in disciplines with lower fire risk. Kart suits are constructed for abrasion resistance rather than flame protection, using leather, nylon, or Cordura. Motorcycle leathers similarly prioritise abrasion resistance and prohibit nylon and spandex, with fire-resistant undergarments remaining optional.
Before purpose-made fire suits, most racing series imposed no uniform requirements. In early NASCAR events, drivers and crew commonly wore jeans and ordinary street clothes. The American firm Hinchman had produced specialised racing suits from the mid-1920s, worn by drivers including Babe Stapp and Pete DePaolo, but these were not designed for flame protection.
A series of fatal fires in the late 1950s and early 1960s accelerated the shift towards flame-resistant clothing. In 1959, Jerry Unser died of burns sustained in a practice crash at the Indianapolis 500, after which all Indy 500 competitors were required to wear fire-retardant clothing. In 1963 the FIA assumed driver-safety responsibility in its series and mandated fire suits for Formula One. In 1964 the NHRA followed suit, and by the end of that year — following the death of Fireball Roberts in a crash at NASCAR's World 600 — virtually all NASCAR competitors had adopted fire suits voluntarily despite no formal rule.
In 1964 the Indianapolis 500 witnessed the deaths of Dave MacDonald and Eddie Sachs in a seven-car crash on the second lap, further underscoring the need for standardised protection. Safety pioneers Jim Deist and Bill Simpson developed some of the first purpose-built fire suits in this period, both initially using aluminised construction for flame resistance. Simpson's first suit was a modified cotton boilersuit.
The introduction of Nomex transformed the field. In 1966 Simpson met NASA astronaut Pete Conrad, who introduced him to the Nomex material used in Apollo programme spacesuits. DuPont simultaneously approached Hinchman about Nomex suit production. Driver Mel Kenyon wore a Nomex suit by Hinchman at that year's Indianapolis 500. Simpson's company released the first commercial Nomex suit, marketed as the "Heat Shield Firesuit", in 1967, and thirty of the thirty-three starters at that year's Indianapolis 500 wore it.
Subsequent decades brought further refinement. In 1975 the FIA introduced its current fire-suit standard. In 1979, several Formula One drivers including Niki Lauda, Mario Andretti, and Carlos Reutemann began using bulky five-layer suits built to NASA specifications. In the mid-1980s suit design evolved to incorporate prominent sponsor branding, requiring patch materials that are themselves fire-resistant. In 1994 the FIA mandated fire suits for Formula One pit crew members to coincide with the reintroduction of refuelling. NASCAR officially mandated suits for both drivers and pit-stop crew members in 2002, making it one of the last major sanctioning bodies to formalise the requirement.
Since the 1980s racing suits have carried extensive sponsor liveries mirroring the designs of the race cars, making the suits a significant commercial canvas. Modern suits often use printed logos rather than sewn patches to save weight, since every sponsor patch must itself meet fire-resistance standards.
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