1
 
                                 TREADCO, INC.
                             1101 SOUTH 21ST STREET
                           FORT SMITH, ARKANSAS 72901
 
                                 March 23, 1999
 
Dear Stockholder:
 
     Enclosed for your consideration is a Recommendation Statement, dated March
23, 1999 of Treadco, Inc., a Delaware corporation (the "Company") relating to
the Offer to Purchase, dated March 23, 1999 (the "Offer to Purchase") pursuant
to which Arkansas Best Corporation, a Delaware corporation ("Parent") is making
an offer to purchase all the outstanding shares (not owned by Parent) of the
Common Stock, par value $0.01 per share (the "Common Stock"), including
associated common stock purchase rights (the "Rights," and together with the
Common Stock, the "Shares") of the Company at $9.00 per Share, net to the seller
in cash, without interest, upon the terms and conditions set forth in the Offer
to Purchase. Enclosed is a copy of Parent's Offer to Purchase and related
materials, including a Letter of Transmittal to be used for tendering your
Shares.
 
     THE BOARD OF DIRECTORS OF THE COMPANY, UPON THE RECOMMENDATION OF A SPECIAL
COMMITTEE OF INDEPENDENT DIRECTORS (THE "SPECIAL COMMITTEE"), HAS UNANIMOUSLY
APPROVED THE OFFER (THE "OFFER") AND RELATED MERGER (THE "MERGER") REFERRED TO
IN THE RECOMMENDATION STATEMENT AND THE OFFER TO PURCHASE AND HAS DETERMINED
THAT THE OFFER AND THE MERGER, TAKEN TOGETHER, ARE FAIR TO, AND IN THE BEST
INTERESTS OF, THE STOCKHOLDERS OF THE COMPANY (OTHER THAN THE PARENT) AND
RECOMMENDS THAT THE STOCKHOLDERS OF THE COMPANY ACCEPT THE OFFER AND TENDER
THEIR SHARES.
 
     The recommendation of the Board of Directors of the Company, the background
of the Offer and Merger, the opinion and a summary of the analysis of the
financial advisor to the Special Committee, and other relevant information is
set forth in detail in the attached Recommendation Statement, and Parent's Offer
to Purchase. You are encouraged to review these materials carefully before
making a decision with respect to the Offer.
 
                                            Sincerely,
 
                                            John R. Meyers
                                            President and Chief Executive
                                            Officer