Executive Change · Company Update

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549     FORM 8-K     CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported) September 2, 2025     PACCAR Inc (Exact name of registrant as specified in its charter)       Delaware   001-14817   91-0351110 (State or other jurisdiction of incorporation)   (Commission File Number)   (IRS Employer Identification No.) 777 106 th Avenue NE , Bellevue , WA 98004 (Address of principal executive offices) (Zip Code) Registrant’s telephone number, including area code (425) 468-7400     Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2.):   ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act:   Title of each class   Trading Symbol(s)   Name of each exchange on which registered Common stock, $1 par value   PCAR   The NASDAQ Stock Market Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). Emerging growth company  ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐       Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. (b) On September 2, 2025, Darrin C. Siver, Executive Vice President, announced his retirement from PACCAR after 32 years of service. Mr. Siver’s retirement is effective January 5, 2026.   Item 8.01. Other Events John N. Rich, Senior Vice President and Chief Technology Officer, will maintain responsibilities for PACCAR’s global technology initiatives and will assume responsibilities for Peterbilt Motors Company effective January 5, 2026. Laura J. Bloch, Senior Vice President, will maintain responsibilities for Kenworth Truck Company and PACCAR Parts and will assume responsibilities for Corporate Quality and Purchasing effective January 5, 2026. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.         PACCAR Inc Date: September 5, 2025     By:   /s/ M. K. Walton       M. K. Walton Vice President and General Counsel