Rush Enterprises (RUSHA) 10-Q 2008 Q3 Quarterly report

EXHIBIT 32.2

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with this quarterly report of Rush Enterprises, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2008, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Steven L. Keller, Vice President and Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act
of 1934; and

2.The information contained in the Report fairly presents, in all material respects, the financial condition and
results of operations of the Company.

By:	/S/ STEVEN L. KELLER
Name:	Steven L. Keller
Title:	Vice President and Chief Financial Officer
Date:	November 10, 2008

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.