SFI racewear guide
How SFI rates suits, gloves, underwear and shoes, how the main materials and constructions compare, and what to check before you put your brand on a certified product.
SFI 3.2A/1 vs 3.2A/5
| SFI 3.2A/1 | SFI 3.2A/5 | |
|---|---|---|
| Minimum TPP (specification) | 6 cal/cm² | 19 cal/cm² |
| Cuircon construction | Single layer, FR-treated cotton (Proban®) | Two-layer: woven outer shell over an inner layer, 100% Nomex® meta-aramid, outer and inner layer |
| Fabric weight | 295 g/m² | 330 g/m² total (150 g/m² outer + 180 g/m² inner) |
| Recorded material TPP | TPP 10 | TPP 21.6 |
| Tests in the specification | The same for both: TPP, flammability, thread and zipper heat resistance, construction requirements | |
| Pages | SFI 3.2A/1 suits | SFI 3.2A/5 suits |
Both ratings come from the same specification and the same tests. The difference is the minimum TPP of the material: 6 cal/cm² for /1 and 19 cal/cm² for /5. In Cuircon's material range, the /1 construction is a single layer of Proban® FR cotton and the /5 construction is a two-layer Nomex® system (see the materials library). Series rules differ: some, such as SCCA time trials, accept /1 only over fire-resistant underwear, and many set /5 as the minimum. Check the rulebook of the series the suit is for.
Minimum TPP from SFI Specification 3.2A — Driver Suits. Construction, weight and recorded TPP from Cuircon's materials library; a material figure is not a garment certification.
Nomex® vs Proban®
| Nomex® 2-Layer Suit System | Proban® FR Cotton | |
|---|---|---|
| Composition | 100% Nomex® meta-aramid, outer and inner layer | FR-treated cotton (Proban®) |
| Fire resistance | Inherent — the protection is in the fibre and does not wash out | Treated — cotton finished with the Proban® flame-retardant process |
| Weight | 330 g/m² total (150 g/m² outer + 180 g/m² inner) | 295 g/m² |
| Construction | Two-layer: woven outer shell over an inner layer | Single layer |
| Recorded TPP | TPP 21.6 | TPP 10 |
| Used for | Auto racing suits, Two-piece race suits, Custom SFI-5 suits | Entry-level auto racing suits, Single-layer race suits |
Nomex® suit system · Proban® FR cotton · Request fabric swatches
One layer vs two layers
Single-layer suits
One layer of fire-resistant fabric, typically a treated FR cotton twill. It is light and cool, and is the usual route to an SFI 3.2A/1 rating. Because a single layer leaves little insulating air, series that allow /1 suits often require fire-resistant underwear beneath them.
Two-layer suits
An outer shell and an inner layer, usually meta-aramid, with air trapped between them. The air gap does much of the insulating work, so two layers can reach a higher thermal rating than one heavier layer. This is the common construction for SFI 3.2A/5 suits.
Three-layer suits
An outer shell, an insulating middle layer and a comfort inner layer. The extra layer raises thermal protection, at the cost of weight and heat build-up in the cockpit. It is chosen where a series or discipline asks for higher ratings.
What decides the rating
Under SFI 3.2A the rating is based on the thermal protection of the material as tested, regardless of the number of layers, and underwear worn beneath the suit does not count. Under FIA 8856-2018 each component assembly must reach the minimum heat-transmission time. Layer count is a means, not the measure.
Understanding TPP
Thermal Protective Performance (TPP) measures how much heat a material holds back before the heat passing through it would cause a second-degree burn. SFI expresses it in cal/cm². The higher the TPP, the higher the grade a material can reach.
The suit material is tested for Thermal Protective Performance (TPP). The grade printed on the patch is the highest grade whose minimum TPP the material reaches. The rating applies to the material as built, regardless of how many layers it has, and underwear worn beneath the suit does not count towards it.
| SFI grade | Minimum TPP (cal/cm²) | W·sec/cm² |
|---|---|---|
| 3.2A/1 | 6 | 25.1 |
| 3.2A/3 | 14 | 58.6 |
| 3.2A/5 | 19 | 79.6 |
| 3.2A/10 | 38 | 159.1 |
| 3.2A/15 | 60 | 251.2 |
| 3.2A/20 | 80 | 335.0 |
| 3.2A/25 | 100 | 418.7 |
| 3.2A/30 | 120 | 502.4 |
Racing glove construction
Each finger and thumb must have its own section. A glove is graded by the TPP of its top covering. For grades above /1, the palm side must reach at least 40% of the top's required TPP and the forchettes (finger sides) at least 20%, or grade 1 if that is higher. A glove that misses those values is downgraded until every section conforms.
Leather palms are allowed, but the palm and forchettes may not be leather alone: a layer the manufacturer represents as fire-resistant must separate the leather from the hand.
Glove seams have their own flammability test.
| SFI grade | Top | Palm side | Forchettes |
|---|---|---|---|
| 3.3/1 | > 6 | n/a | n/a |
| 3.3/5 | ≥ 19 | ≥ 7.6 | ≥ 6.0 |
| 3.3/10 | ≥ 38 | ≥ 15.2 | ≥ 7.6 |
| 3.3/15 | ≥ 60 | ≥ 24.0 | ≥ 12.0 |
| 3.3/20 | ≥ 80 | ≥ 32.0 | ≥ 16.0 |
| 3.3/25 | ≥ 100 | ≥ 40.0 | ≥ 20.0 |
| 3.3/30 | ≥ 120 | ≥ 48.0 | ≥ 24.0 |
Racing shoe construction
Underclothing, hoods, socks, helmet supports, harness pads and sports bras must reach a minimum TPP of 6.0 cal/cm².
Shoes and boots must use fire-resistant material in the non-sole area and reach a minimum TPP of 19.0 cal/cm².
Fabric layers must average 2.0 seconds or less of after-flame and 6 inches or less of char length, with no melting or dripping.
Suit fit and measurement
Box quilting
Stitching the layers together in a grid of boxes keeps them from shifting and holds the air gap evenly across the panel. Quilt size and pattern also change how stiff or soft the suit feels.
Radial and floating sleeves
A radial sleeve is cut in one piece with the shoulder, so the arm can reach forward to the wheel without lifting the body of the suit. A floating sleeve adds a gusset under the arm for the same purpose. Both are about freedom at the shoulder in a seated position.
Pre-shaped knees and elbows
Panels cut to the bent shape of a seated driver, so fabric does not bunch behind the knee or pull across the elbow.
Standard sizing
Patterns graded across adult and youth size ranges. This suits teams, retailers and rental fleets ordering by size breakdown.
Size & measurement guideCustom sizing
A standard pattern adjusted for length, girth or sleeve, for drivers between sizes.
Made-to-measure
A pattern cut from the driver's own measurements, taken with the measurement guide and recorded on the order form.
Custom suit order formMaterial and garment testing
SFI tests the materials and the made-up garment, not the fibre name on the label.
- Flammability: each tested layer must average 2.0 seconds or less of after-flame and 6 inches (152 mm) or less of char length, and any melting or dripping fails the test.
- Thread heat resistance and zipper heat resistance: the sewing thread and the zipper with its tape are tested separately, and the zipper must not melt, drip, separate or ignite.
- Expansion or comfort gussets, where used, must reach the same minimum TPP as the rest of the suit.
- Closures: zippers must have metal teeth and fire-retardant tape, and any zipper or hook-and-loop closure must be covered by fire-resistant material.
- Cuffs at the wrists and ankles are required and must be fire-resistant.
- Embroidered logos are permitted by the specification. Stretch panels, gussets and any cool-suit openings must not reduce the suit below its stated rating.
- Private label: if a suit is sold under another brand name, the certifying manufacturer must still be identified on a label inside the suit.
Labelling and certification requirements
Certification is made by the manufacturer. SFI states that products in the programme are not certified, endorsed or approved by SFI itself: the patch means the manufacturer has represented that the product passed the required tests, and SFI monitors the programme through test reports and audits.
The conformance patch is sewn to the left sleeve between the wrist and the shoulder (not on the cuff), or on the back centred no more than 4 inches below the collar. On pants it goes on the left side or rear centre at the belt line.
Suits certified at /10 or higher are inspected every five years by the certifying manufacturer. A suit that passes receives a new conformance label marked with the year of inspection.
Every individual item carries its own patch: on each glove at the upper cuff (or visibly inside it), on the left sleeve or shirt hem of underwear tops, at the left belt line of pants, on the lower front bib of hoods, above the ankle on each sock, and on the upper outside or visibly inside each shoe.
Compare our auto racing products
Filter the range, then tick up to three products to compare side by side. Status shows only what is verified.
| Compare | Product | Type | Standard named | Status | Sizes | Minimum order | Lead time |
|---|---|---|---|---|---|---|---|
| Custom SFI 3.2A/5 Auto Racing Suit – 2 Layer | Suit | SFI 3.2A/5 | In development for certification | XS – 3XL | Contact us for order quantities | Confirmed upon design approval and order quantity | |
| Private Label SFI 3.2A/5 Racing Suit | Suit | — | In development for certification | On request | Minimum order quantity depends on the selected construction, color combination, customization, branding, and production requirements. Contact Cuircon International with your estimated order quantity for a tailored quotation. | Production lead time depends on order quantity, material availability, artwork approval, sample requirements, and final specifications. A confirmed production schedule will be provided with the quotation or order confirmation. | |
| 2 Layer SFI 5 Custom Suit | Suit | — | In development for certification | On request | 1 piece | Approximately 20–30 days depending on customization and order quantity | |
| Auto Racing 2 Piece Suit | Suit | SFI 3.2A/1 or SFI 3.2A/5 | In development for certification | Adult, ladies and made to measure | Minimum order quantity confirmed per design complexity and material selection. | Lead time depends on customization level and order quantity — confirmed at quoting stage. | |
| Custom SFI 3.2A/1 Racing Suit – Single Layer FR Cotton | Suit | SFI 3.2A/1 | In development for certification | XS – 4XL | Contact us for minimum order quantities | Confirmed based on order quantity and customization | |
| Auto Racing Gloves | Gloves | SFI 3.3/5 | In development for certification | Youth 4XS – Adult 3XL (sizes 4–13) | Minimum order quantity confirmed per design complexity. | Confirmed at quoting stage based on order specification. | |
| SFI 3.3/5 Nomex Auto Racing Gloves – Custom Fire-Resistant Racing Gloves | Gloves | SFI 3.3/5 | In development for certification | XS – 4XL | On request | On request | |
| Private Label SFI Racing Shoes | Shoes | SFI 3.3/5 | In development for certification | EU 34–48 (US men's 3–13.5) | Minimum order quantity depends on the selected materials, construction, sizing, branding, and production requirements. Contact Cuircon International with your estimated order quantity to discuss a suitable manufacturing arrangement. | Lead time depends on material availability, sample approval, order quantity, customization, and production scheduling. The estimated timeline will be confirmed with your quotation or order confirmation. | |
| Custom SFI 3.2A/1 Racing Jacket – Single Layer FR Cotton | Jacket / trousers | SFI 3.2A/1 | In development for certification | XS – 4XL | Order a Single Jacket | Confirmed according to quantity and customization | |
| Custom SFI 3.2A/1 Racing Pants – Single Layer FR Cotton | Jacket / trousers | SFI 3.2A/1 | In development for certification | XS – 4XL | Contact us for minimum order quantities | Confirmed based on quantity and customization | |
| Classic High-Top SFI Racing Shoes | Shoes | SFI 3.3/5 | In development for certification | EU 34–48 (US men's 3–13.5) | Minimum order quantities depend on materials, construction, sizing, branding, and production requirements. Contact Cuircon International to discuss your target quantity and available manufacturing options. | Lead time depends on material availability, sample approval, order quantity, customization, and production scheduling. The expected timeline will be confirmed with your quotation. | |
| SFI 3.3 Nomex® Fire-Resistant Racing Base Layer / Undergarments – 2-Piece White Set | Underwear | SFI 3.3 | In development for certification | XS – 3XL | Available on request, depending on size assortment, specifications, and customization requirements. | Confirmed according to sample approval, order quantity, material availability, and production requirements. | |
| Apex Geo Nomex® Auto Racing Shoes | Shoes | SFI 3.3/5 | In development for certification | XS - 4XL | 1-5 | Sample and production lead times are confirmed with your quotation, based on material availability, quantity and approval of the final specifications. |
"Standard named" is the standard a product is designed around. "Status" is Certified only where a verified, current certification record exists; otherwise the status for your order is confirmed in the quotation.
Sources: SFI Specification 3.2A (PDF), effective 26 June 2020 · SFI Foundation: protective gear specifications and manufacturer lists · SCCA Time Trials: driver clothing (example of series rules) · SFI Specification 3.3 (PDF), effective 1 April 2022 · SFI Foundation: protective gear specifications and manufacturer lists. Full guides: SFI 3.2A · SFI 3.3.