I am Exporting Rubber Tailgate Body seals for Refuse Vehicles as in dustcarts to go to Costa Rica
You can get the commodity code by going to http://www.acorninteractive.co.uk/community/glossary
Go to tariff code and there is a link for you to get the code.
Hope that helps
You could try HS code 4016 9957
As you will know the exact specification of your products, you are best placed to establish the correct HC Commodity / Tariff code.
You can find the correct code using the online UK Trade Tariff:
Alternatively, you may wish to call the Tariff Classification helpline on 01702 366077. The call handler can classify a maximum of three products per call.