If a Japanese customer asks you to use Malaysian wheels, you must ask the Japanese to buy the wheels. You should not pay any cost for the wheels, otherwise you cannot accept this kind of sale, because there is a possibility that the Japanese and Malaysians will partner up. Liar.
If the Japanese agree to pay for the wheels, you can apply for the processing manual when importing, and you can import the wheels duty-free. After the vehicle is exported, you can write off the processing manual.
One more question, do you have import and export rights? If you do not have import and export rights, you cannot complete the transaction alone. You must also find a foreign trade company to act as an agent for the processing contract. In this case, the cost will increase, and it may be difficult for the business to succeed.