The government is being urged to revise a draft rubber bill, particularly for the collection of cess from tyre exporters.
The tax is seen as a setback to the competitiveness of the overall tyre manufacturing sector.
Finbarr O'Connor, newly appointed chairman of Thai Automobile Tyre Manufacturers Association (Tatma), said the industry was concerned about the new rubber bill, which states that cess covers all exported rubber products.
Currently, only rubber sheets are subject to this fee for shipment outside Thailand, 90 satang to 5.50 baht a kilogramme, depending on the price of rubber.
The Office of the Rubber Replanting Aid Fund (ORRAF) uses the cess revenue mainly to replant and replace degraded rubber trees.
Mr O'Connor said the charge would hurt tyre makers' competitiveness, as additional costs must be added to automotive tyre prices in the future.
"Tatma is concerned about the unnecessary fee under the new bill," he said.
"Tyre manufacturers want to export as much as they can, and they need all the encouragement from the government."
The draft rubber law passed its first reading in the National Legislative Assembly last December.
It will replace the existing eight laws governing the rubber industry and set up the Rubber Authority of Thailand as the central body to oversee the industry, managing funds to support it and promoting the country as a rubber production hub.
Under the draft bill, three Agriculture Ministry agencies will be merged into the new state enterprise — the Rubber Research Institute, the ORRAF and the Rubber Estate Organization.