The rubber board saw its split reverse today. Natural rubber at ¥19,390/t closed down 1.5%, while butadiene rubber at ¥16,470/t rose 0.67%, pulling the NR premium over BR from above ¥4,000 last month down to ¥2,920.

Butadiene rubber's floor is in its feedstock. Concentrated butadiene plant turnarounds and tight external availability held up the cost base of BR; even with mediocre tire off-take, the synthetic would not fall. Natural rubber, by contrast, gave back the premium built on Southeast Asian rainfall and leaf-fall disease trades, as destocking at Qingdao bonded warehouses slowed and longs took profit.

For tire makers the narrowing NR–BR spread opens a formulation shift toward the synthetic side. BR is nearly ¥2,900 cheaper than NR; each 5-point lift in blend ratio shaves raw-rubber cost off a full-steel tire. But once butadiene units return and supply loosens, BR's cost support collapses, so the shift must be timed against the turnaround calendar, not chased at highs.

SNSUC runs title transfer and warehousing on the base-oil and synthetic-rubber line rather than touching formulations. We still track the NR–BR spread because it maps directly to downstream tire-makers' procurement rhythm, which in turn drives turnover and pledge ratios of synthetic rubber in bonded warehouses.