Butadiene rubber added 2.77% to ¥17,245/t while natural rubber eased 0.52% to ¥19,170/t; the spread between the two compressed to ¥1,925/t, reopening the compound-substitution window.

Natural rubber settled at Y19,580/t (-0.53%) while butadiene rubber rose to Y16,455/t (+0.58%). The gap between the two shrank from Y3,800-4,450 to Y3,125. A tighter gap trims the cost penalty of using natural rubber, nudging tire recipes back toward the natural leg.