Natural rubber front-month settled at ¥20,130/t, up 2.13% on the day. Butadiene rubber (BR) settled at ¥16,555/t, up 4.32%. BR moved faster than NR, compressing the NR-BR spread from ¥4,095/t in early August to ¥3,575/t — a two-month low.

For a tire compounder the spread is a direct switch signal. BR is synthetic and tracks crude and butadiene; NR is an agricultural product driven by plantation weather and warehouse receipts. When BR gets relatively expensive, the substitutable portion of the mix shifts toward NR. Lifting NR share by five percentage points in a passenger-car tire formulation trims raw-material cost per tire by a visible margin.

NR is not freely swappable, though. At ¥20,130/t the bonded warehouse receipt is the hedging anchor: a plant fixes an equal physical line on SNSUC's bonded digital receipt while pricing on the exchange, then draws the stock once the formulation switch settles — avoiding a squeeze on both legs. Title on the receipt carries a SHA-256 fingerprint, so ownership is clear before delivery and banks accept it as collateral.

Two signals to watch this week: if BR keeps outrunning NR, the spread tightens further and the NR switch pays more; and bonded receipt velocity — with pledge funding at T+0, the capital tied up in locking stock drops from weeks to the same day, freeing plant working capital. Do not chase the high; wait for the spread to recover above ¥4,000/t before rebuilding BR exposure.