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| Size | US | Chest | Waist | Hip |
|---|---|---|---|---|
| XS | 2 | 32 | 24 - 25 | 33 - 34 |
| S | 4 | 34 - 35 | 26 - 27 | 35 - 26 |
| M | 6 | 36 - 37 | 28 - 29 | 38 - 40 |
| L | 8 | 38 - 29 | 30 - 31 | 42 - 44 |
| XL | 10 | 40 - 41 | 32 - 33 | 45 - 47 |
| XXL | 12 | 42 - 43 | 34 - 35 | 48 - 50 |
Sprint car, drag, dirt late model, karting, road racing — the exact SFI rating you actually need for your discipline, and why the rating goes up when the class does.
A practical, discipline-by-discipline guide to picking the right SFI 3.2A rating for the car you actually race.
Every racer has had this moment: you're filling out an order form or staring at a suit on a shelf, and the rating reads SFI 3.2A/1, 3.2A/5, 3.2A/15, or higher. You know higher is more protection. You know your sanctioning body has a minimum. What you actually want to know is one thing: which rating do I need for what I race?
This guide answers that question for every discipline HS Race Gear builds for — sprint car, drag, dirt late model, road racing, karting, and powerboat. No fluff. If you want the background theory on what SFI ratings actually measure, read SFI Ratings Explained next. If you want to know what to order today, keep reading.
This is the answer most racers actually need. Every line below assumes you're competing in a sanctioned event. Always confirm against your specific series' current rulebook — sanctioning bodies revise their tech requirements, sometimes mid-season.
The rule of thumb: as horsepower, top speed, and elapsed-time pressure go up, the SFI rating climbs in step. The cost of "more rating than I need" is comfort. The cost of "less rating than I need" is failing tech — or worse.
Every SFI-certified racing suit has a sewn-in label with the spec number, the rating, and the manufacturer details. Here's what each part actually means:
If the label is faded, missing, or unreadable, the suit will not pass tech inspection — regardless of how protective the materials still are. SFI compliance is a paperwork standard as much as a materials one.
Sprint cars and dirt late models share a similar risk profile: open cockpit, methanol or high-octane gas, rapid fire potential after contact, and abrasion exposure if you're upside-down sliding through the infield. A single-layer SFI 3.2A/1 suit is technically allowed in some entry-level dirt divisions but it's the wrong tool for the job.
What we recommend for sprint car and dirt late model drivers:
The reason SFI 3.2A/5 dominates dirt is simple: it gives you the multi-layer thermal protection you actually need, with enough breathability to survive 30 laps on a hot July night without overheating yourself. SFI 3.2A/10 adds protection for the higher-purse classes but at the cost of weight and warmth.
Drag racing is the discipline where SFI ratings are most strictly tied to performance brackets. The faster you go, the higher the rating must be — and the rule isn't a suggestion. NHRA and IHRA tech officials will turn you away in line if your suit's rating doesn't match your timing slip.
The NHRA ET-to-rating ladder, simplified:
Always cross-reference your specific class in the current NHRA Rulebook before ordering. Sportsman and bracket racing classes have their own variations, and outlaw classes set their own rules.
Heads-up
If you build your car faster than your suit is rated for, you don't qualify to race that pass — even if your suit is otherwise in perfect shape. Buy for the car you intend to build, not the one in the trailer today.
Karting is the discipline most racers ask the most questions about, because the SFI rating story is genuinely different here. Karts don't carry enough fuel for a sustained pool fire, the engines run cooler, and abrasion — not fire — is the primary injury risk in a kart-on-track or kart-on-barrier event.
As a result, most national karting bodies (WKA, SKUSA, Rotax Max Challenge USA) specify CIK-rated karting suits rather than higher SFI tiers. CIK suits are tested for abrasion resistance — exactly the failure mode that karting protects against — while still providing the fire-retardant baseline equivalent to SFI 3.2A/1.
If a karting suit is sold as "SFI 3.2A/5 for karting," it's either over-built (which is fine but adds weight) or marketed wrong. CIK Level 2 with SFI 3.2A/1 baseline is the actual karting standard.
Road racing in the US runs across a half-dozen sanctioning bodies, each with its own tech standards. The big rule: SFI is the dominant standard in the US, FIA 8856-2000 (or the newer 8856-2018) is the dominant standard internationally, and most US series accept either at the same rating tier.
Powerboat racing has SFI requirements that are less well-known than auto-racing's because the sport is smaller and the rulebooks are harder to find online. APBA-sanctioned classes typically require:
The big difference vs auto racing: powerboat suits need to dry quickly between heats and tolerate salt water. Material selection matters more than the SFI number in this segment.
Six things that get racers turned away at tech inspection, in order of how often we see them:
Most sanctioning bodies set a minimum SFI rating per class but don't cap the upper end. You're allowed to wear a 3.2A/15 suit in a class that only requires 3.2A/5 — but should you?
Three reasons to stay at the minimum rating:
Three reasons to go up a tier:
Keep going — more racing-suit guides from the HS Race Gear blog.
Which SFI rating each dirt oval body requires, by class. Street stock through winged sprint car, plus what tech actually checks.
SFI 3.2A is tiered and US-focused; FIA 8856-2018 is single pass/fail and international. Why one won't reliably substitute for the other.
The hidden number behind every SFI rating. Why two SFI 3.2A/5 suits can have different TPP scores, and how to find the actual number.
HS Race Gear builds custom racing suits in every SFI rating from 3.2A/1 through 3.2A/15, made to your measurements. Premium Nomex® construction, unlimited mockup revisions, free shipping on custom suits.
