Loading...
HSChapter 40
U.S. imports of isobutene-isoprene (butyl) rubber (iir) (HS 400231) totaled $1.4M in April 2026, traded with 12 countries.
Importers of Isobutene-Isoprene (Butyl) Rubber (IIR) paid $3K in duties in April 2026 — an effective duty rate of 0.9% on $343K in dutiable value, based on actual customs collections rather than the published tariff schedule.
Last updated: April 2026 dataButyl rubber's near-impermeable barrier to gases makes it the material of choice for tire inner tubes and liners, pharmaceutical stoppers, and industrial seals where air or moisture retention is critical. Canada dominates US supply — a reflection of the major IIR production facilities operated in Canada by global elastomer producers — with India and Thailand also contributing. The entire heading is covered by tariff line 4002310000. Mooney viscosity and isoprene content are the primary specification parameters that differentiate IIR grades for tire versus pharmaceutical applications.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
IIR's extremely low gas permeability and chemical inertness make it suitable for vial stoppers and syringe plungers where container integrity is paramount. When butyl rubber is imported as a finished pharmaceutical closure rather than as raw polymer, it may be subject to FDA review as a drug-contact material. Raw IIR polymer classified under 4002310000 does not itself trigger FDA admissibility review, but downstream finished closures would. Importers should confirm the form of the goods and consult a customs broker if the material is partially fabricated.
Canada's proximity and USMCA trade relationship provide US buyers with logistical and cost advantages, but the concentration of IIR production in a small number of North American facilities means supply disruptions — whether from plant outages or feedstock shortages — can have outsized market impact. Buyers with critical IIR requirements often maintain safety stock or qualify secondary suppliers from India or Japan to hedge against single-source exposure.
Supplier Network
Get discovered by U.S. importers searching for HS 400231 — Isobutene-Isoprene (Butyl) Rubber (IIR). Be the first supplier listed.
Monthly import values over time
HS10 import codes under this HS6 parent. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Duty Collected |
|---|---|---|---|---|
| 4002310000 | ISOBUTENE-ISOPRENE (BUTYL) RUBBER (IIR) | $1.4M | 0.93% | $3K |
ISOBUTENE-ISOPRENE (BUTYL) RUBBER (IIR)
HS10 export codes under this HS6 parent. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 4002310000 | ISOBUTENE-ISOPRENE (BUTYL) RUBBER (IIR) | $3.2M |
ISOBUTENE-ISOPRENE (BUTYL) RUBBER (IIR)
1.2M kg
NEW PNEUMATIC TIRES OF RUBBER, FOR MOTOR CARS
HS 401110
NEW PNEUMATIC TIRES OF RUBBER, FOR BUSES OR TRUCKS
HS 401120
GASKET, WASHERS & OTHER SEALS, OF VULCANIZED RUB
HS 401693
ARTICLES OF SOFT VULCANIZED RUBBER NESOI
HS 401699
MEDICAL/SURGICAL/DENTAL/VET GLOVES, MITTENS, MITTS
HS 401512
NEW PNEUMATIC TIRES OF RUBBER, NESOI
HS 401190
| Port | Imports | Exports | Balance |
|---|---|---|---|
| HOUSTON, TX | -- | $1.5M | +$1.5M |
| PORT HURON, MI | $1.2M | $62K | -$1.1M |
| LAREDO, TX | -- | $1.2M | +$1.2M |