As of June 2015, some good places to find free commercial driver's license general knowledge tests are TruckerCountry.com, CDLTest.co and CDLCareerNow.com. TruckerCountry.com provides general knowledge practice tests in three different modes, including classic, practice and exam mode. Each mode offers seven different practice tests.
CDLTest.co offers a general knowledge test with 66 multiple-choice answers. After answering each question, practice testers can see if they got the answer correct. CDLCareerNow.com offers a practice test with 52 general knowledge questions. To practice, the person selects the correct multiple-choice answer and hits next for the following question. Test takers see immediately if they answered correctly and receive a report of all answers at the end of the test.