The activity is works contract since it is a repair work involving both sale of goods and rendition of service. Please refer to the definition of Works Contract under SEction 65B of the Finance Act, 1994 which states as follows:
"works contract" means a contract wherein transfer of property in goods involved in the execution of such contract is leviable to tax as sale of goods and such contract is for the purpose of carrying out construction, erection, commissioning, installation, completion, fitting out, repair, maintenance, renovation, alteration of any moveable or immovable property or for carrying out any other similar activity or a part thereof in relation to such property;
There is a contract (oral or written) and there is transfer of property in the form of rubber (used for re-rubbersing etc) and the goods in question are leviable to tax as sale of goods, since VAT is paid. Hence it is a works contract.
The material value should suffer VAT and service portion should suffer ST. As per Rule 2A of the Service Tax Valuation Rules, 2006, the service provider is liable to pay the tax by excluding the material value and if it is not possible to seggregate material value, he can pay ST on 70% of the gross value. However, if he is an individual/HUF/Partnership firm and yours is a body corporate, reverse charge mechanism applies under Nofn.30/2012-ST whereby each of you have to pay 50% of the tax.
Hence, service tax is applicable. TDS is a different matter for which you may refer Section 194C of the Income Tax Act, 1961. If TDS is also attracted, both are leviable. While ST is an indirect tax on the value of the activity, TDS is a direct tax on the profit / amount payable to the contractor or job worker.