26 CFR §48.4073-3

1. (a)Sold direct by manufacturer for nontaxable use. The tax does not apply to the sale of tread rubber by the manufacturer to any person for use by that person otherwise than in the recapping or retreading of tires of the type used on highway vehicles. In determining whether tread rubber is sold for a taxable or nontaxable use, the type of vehicle on which the recapped or retreaded tire is to be used, or the actual or intended use of the recapped or retreaded tire, is immaterial. The controlling factor is whether the tire resulting from the recapping or retreading is of a type that is used otherwise than on a highway vehicle. For definition of “tires of the type used on highway vehicles”, see paragraph (c) of § 48.4072-1.
2. (b)Sales for resale for nontaxable use. No sale of tread rubber may be made tax free for resale even though it is known at the time of the sale that the tread rubber will be resold for use otherwise than in the recapping or retreading of tires of the type used on highway vehicles. However, where the tread rubber is resold for such use, the manufacturer who paid the tax on a sale of the tread rubber may secure a refund or credit in accordance with the provisions of section 6416(b)(2) and § 48.6416(b)-2.
3. (c)Evidence required to establish exemption.
   1. (1)To establish the right to sell tread rubber tax free under section 4073(c), the manufacturer must obtain from the purchaser and retain in its possession a properly executed exemption certificate.
   2. (2)Where only occasional sales of tread rubber for exempt use are made to a purchaser, a separate exemption certificate should be furnished for each order. However, where sales are regularly and frequently made to a purchaser for exempt use, a certificate covering all purchases during the period not to exceed 12 calendar quarters is acceptable. The certificates and proper records of invoices, orders, etc., relative to tax-free sales must be kept for inspection by the district director as provided in section 6001 and the regulations in subpart Q.
4. (d)Acceptable form of exemption certificate. The following form of exemption certificate is acceptable for the purposes of this section and must be adhered to in substance:
5. (e)Exemption certificate not obtained prior to filing of manufacturer's excise tax return. If the sale is otherwise exempt but the exemption certificate is not obtained prior to the time the manufacturer files a return covering taxes due for the period during which the sale was made, the manufacturer must include the tax on the sale in its return for that period. However, if the certificate is later obtained, a claim for refund of the tax paid on the sale may be filed, or a credit for the amount may be taken upon a subsequent return, as provided by section 6416(b)(2) and § 48.6416(b)-2.