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HSChapter 40
U.S. imports of halobutyl rubber — chlorobutyl (ciir) & bromobutyl (biir) (HS 400239) totaled $4.3M in April 2026, traded with 10 countries.
Importers of Halobutyl Rubber — Chlorobutyl (CIIR) & Bromobutyl (BIIR) paid $138K in duties in April 2026 — an effective duty rate of 12% on $1.2M in dutiable value, based on actual customs collections rather than the published tariff schedule. Halobutyl Rubber — Chlorobutyl (CIIR) & Bromobutyl (BIIR) imports of $4.3M in April 2026 ran 18% above the year-to-date monthly average of $3.6M.
Last updated: April 2026 dataHalogenation of butyl rubber — chlorination to produce CIIR or bromination to produce BIIR — introduces reactive halogen sites that dramatically improve cure compatibility with general-purpose rubbers and accelerate vulcanization rates, making halobutyl the standard inner liner compound in tubeless radial tires. Canada and the United Kingdom are the leading US suppliers, reflecting the limited number of global facilities capable of the halogenation process. Both CIIR and BIIR are classified under the single tariff line 4002390000. BIIR's faster cure rate and better adhesion to tire carcass compounds have made it the preferred choice for high-performance and truck tire liners, while CIIR remains competitive in cost-sensitive applications.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
Both CIIR and BIIR fall under the same tariff line (4002390000), so the distinction does not affect duty liability. However, commercial invoices and certificates of analysis should clearly identify the halogen type (chloro vs. bromo), Mooney viscosity, and halogen content percentage, as these are the parameters buyers and compounders use to verify grade conformance. Accurate documentation also supports any future scope ruling or audit defense.
Halobutyl production requires dedicated halogenation reactors integrated with butyl rubber polymerization lines, representing significant capital investment that limits the number of viable production sites globally. The Canadian facilities benefit from proximity to US tire manufacturers and established feedstock supply chains, while UK production reflects legacy investments by major elastomer companies. This concentration means US importers have limited alternative qualified sources, making long-term supply agreements and inventory management particularly important.
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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 |
|---|---|---|---|---|
| 4002390000 | HALO-ISOBUTENE-ISOPRENE RUBBER, NESOI | $4.3M | 11.68% | $138K |
HALO-ISOBUTENE-ISOPRENE RUBBER, NESOI
HS10 export codes under this HS6 parent. Source: U.S. Schedule B export classification.
| Code | Description | Export Value |
|---|---|---|
| 4002390000 | HALO-ISOBUTENE-ISOPRENE RUBBER, NESOI | $29.3M |
HALO-ISOBUTENE-ISOPRENE RUBBER, NESOI
12.4M 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
| State | Imports | Exports | Balance |
|---|---|---|---|
| Louisiana | $870K | $18.2M | +$17.3M |
| Texas | $80K | $10.6M | +$10.6M |
| South Carolina | $1.2M | -- | -$1.2M |
| Port | Imports | Exports | Balance |
|---|---|---|---|
| NEW ORLEANS, LA | $872K | $13.9M | +$13.0M |
| HOUSTON, TX | $192K | $9.6M | +$9.4M |
| LAREDO, TX | -- | $3.7M | +$3.7M |