If the Japanese agree to pay for the wheels, they can apply for a processing manual when importing, and they can import the wheels duty-free. After the whole vehicle is exported, the processing manual can be written off.
One more question, do you have import and export rights? Without the right to import and export, it is impossible to complete the business alone. You must also find a foreign trade company as an agent for processing contracts. In this way, the cost will increase, and business may be difficult to succeed.