1
                                                                     EXHIBIT 4.6

         SUPPLEMENTAL INDENTURE, dated as of February 22, 1999 (the
         "Supplemental Indenture"), among CALIFORNIA TIRE COMPANY, a California
         corporation (the "New Guarantor"), THE J.H. HEAFNER COMPANY, INC., a
         North Carolina corporation (the "Company"), each other existing
         Subsidiary Guarantor under the Indenture referred to below, and FIRST
         UNION NATIONAL BANK, as Trustee (the "Trustee") under the Indenture
         referred to below.                                                     
         ----------------------------------------------------------------------

                              W I T N E S S E T H:

         WHEREAS, the Company, the then existing Subsidiary Guarantors and the
Trustee have heretofore executed and delivered an Indenture, dated as of May 15,
1998 (as amended, supplemented, waived or otherwise modified, the "Indenture"),
providing for the issuance of an aggregate principal amount of $100 million of
10% Senior Notes due 2008 of the Company (the "Securities");

         WHEREAS, Section 4.12 of the Indenture provides that the Company is
required to cause each domestic Restricted Subsidiary (other than an Immaterial
Subsidiary that is neither a borrower nor a guarantor under the Credit Facility)
to execute and deliver to the Trustee a Guaranty Agreement pursuant to which
such Restricted Subsidiary will Guarantee payment of the Securities on the same
terms and conditions as those set forth in Article 10 of the Indenture;

         WHEREAS, the Company is causing the New Guarantor to execute this
Supplemental Indenture in order to comply with the terms of Section 4.12 of the
Indenture and the New Guarantor intends thereby to become bound as a Subsidiary
Guarantor; and

         WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee and the
Company are authorized to execute and deliver this Supplemental Indenture
amending the Indenture, without the consent of any Holder (as defined in the
Indenture);

         NOW, THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, the New
Guarantor, the Company, the existing Subsidiary Guarantors and the Trustee
mutually covenant and agree for the equal and ratable benefit of the holders of
the Securities as follows:

                                    ARTICLE I

                                   Definitions

         SECTION 1.1 Defined Terms. As used in this Supplemental Indenture,
terms defined in the Indenture or in the preamble or recital hereto are used
herein as 

   2

therein defined, except that the term "Holders" in this Supplemental Indenture
shall refer to the term "Holders" as defined in the Indenture and the Trustee
acting on behalf or for the benefit of such Holders. The words "herein,"
"hereof" and "hereby" and other words of similar import used in this
Supplemental Indenture refer to this Supplemental Indenture as a whole and not
to any particular section hereof.

                                   ARTICLE II

                        Agreement to be Bound; Guarantee

         SECTION 2.1 Agreement to be Bound. The New Guarantor hereby becomes a
party to the Indenture as a Subsidiary Guarantor and as such will have all of
the rights and be subject to all of the obligations and agreements of a
Subsidiary Guarantor under the Indenture. The New Guarantor agrees to be bound
by all of the provisions of the Indenture applicable to a Subsidiary Guarantor
and to perform all of the obligations and agreements of a Subsidiary Guarantor
under the Indenture.

         SECTION 2.2 Guarantee. The New Guarantor hereby fully, unconditionally
and irrevocably guarantees, jointly and severally with each other Subsidiary
Guarantor, to each Holder of the Securities and the Trustee and its successors
and assigns, the full and punctual payment when due, whether at maturity, by
acceleration, by redemption or otherwise and within applicable grace periods, of
the Obligations pursuant to Article 10 of the Indenture and subject to the terms
and conditions of the Indenture.

                                   ARTICLE III

                                  Miscellaneous

         SECTION 3.1 Notices. All notices and other communications to the New
Guarantor shall be given as provided in Section 11.02 of the Indenture.

         SECTION 3.2 Parties. Nothing expressed or mentioned herein is intended
or shall be construed to give any Person, firm or corporation, other than the
Holders and the Trustee, any legal or equitable right, remedy or claim under or
in respect of this Supplemental Indenture or the Indenture or any provision
herein or therein contained.

         Section 3.3 Governing Law. This Supplemental Indenture shall be
governed by the laws of the State of New York, but without giving effect to
applicable principles of conflicts of law to the extent that the application of
the laws of another jurisdiction would be required thereby.

         Section 3.4 Severability Clause. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or 



2
   3

impaired thereby and such provision shall be ineffective only to the extent of
such invalidity, illegality or unenforceability.

         Section 3.5 Ratification of Indenture; Supplemental Indenture Part of
Indenture. Except as expressly supplemented hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Securities
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

         Section 3.6 Counterparts. The parties hereto may sign one or more
copies of this Supplemental Indenture in counterparts, all of which together
shall constitute one and the same agreement.

         Section 3.7 Headings. The headings of the Articles and the sections in
this Supplemental Indenture are for convenience of reference only and shall not
be deemed to alter or affect the meaning or interpretation of any provisions
hereof.

         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first above written.


                          THE J.H. HEAFNER COMPANY, INC.


                          By:  /s/ William H. Gaither
                             ---------------------------
                             Name: William H. Gaither
                             Title: President and Chief Executive Officer


                          CALIFORNIA TIRE COMPANY,
                             as a Guarantor


                          By:  /s/ William H. Gaither
                             ---------------------------
                             Name: William H. Gaither
                             Title: Chief Executive Officer


                          By:  /s/ J. Michael Gaither
                             ---------------------------
                             Name: J. Michael Gaither
                             Title: Vice President, General Counsel & Secretary


                          OLIVER & WINSTON, INC.

                          By:  /s/ William H. Gaither
                             ---------------------------
                             Name: William H. Gaither
                             Title: Chief Executive Officer


                          By:  /s/ J. Michael Gaither
                             ---------------------------
                             Name: J. Michael Gaither
                             Title: Vice President, General Counsel & Secretary




3
   4



                        THE SPEED MERCHANT, INC.


                        By:  /s/ William H. Gaither
                           ---------------------------
                           Name: William H. Gaither
                           Title: Chief Executive Officer

                        By:  /s/ J. Michael Gaither
                           ---------------------------
                           Name: J. Michael Gaither
                           Title: Vice President, General Counsel & Secretary

                        PHOENIX RACING, INC.


                        By:  /s/ William H. Gaither
                           ---------------------------
                           Name: William H. Gaither
                           Title: Chief Executive Officer

                        By:  /s/ J. Michael Gaither
                           ---------------------------
                           Name: J. Michael Gaither
                           Title: Vice President, General Counsel & Secretary

                        FIRST UNION NATIONAL BANK,
                          as Trustee


                        By:  /s/ Shannon Schwartz
                           ---------------------------
                           Name: Shannon Schwartz
                           Title: Assistant Vice President



4