The most active March 2006 rubber contract on the Tokyo Commodity Exchange slumped 5.1 yen per kg to 189.2 yen. Other contracts shed between 4.7 to 5.5 yen.
"TOCOM is still going down and buyers stay away from the market. They may be looking for even lower prices," said one Thai trader in the southern town of Hat Yai.
The Japanese market sets the tone for global prices of the once red-hot market. Heavy rains in some areas in Thailand, the world's top rubber producer and exporter have subsided, but they continue to limit rubber supplies.
"Rain is on and off. But in the deep south area further down in Hat Yai it still rains sometimes during the night, disrupting tapping activities," said the Thai trader.
Some dealers said falls in futures markets might be a correction as prices should be firmer in the next days. The cited hopes a rise in crude oil prices could convince bulls to return to the rubber market. "The market is uncertain, but most suppliers are not willing to sell at even lower prices," said one Singapore dealer.
Offers for tyre-grade Standard Thai Rubber, or STR20 block, for December and January shipments were unchanged at $1.67 a kg. Dealers were bidding at $1.65 per kg compared with $1.66 on Wednesday.
The Indonesian market, which saw tyre makers purchasing tyre-grade SIR20 this week, showed little activity on Thursday.
The price of SIR20 for January shipment was virtually unchanged at $1.61 a kg. Goodyear Tire & Rubber Co, the largest US tyre maker, bought tyre-grade SIR20 overnight at around $1.60 a kg, free on board Plumbing, on Sumatra island. Raw material prices for export-grade rubber in Thailand benchmark unsmoked rubber sheet grade 3, or USS3, was flat at 64 baht a kg.