Work out which type of CDL you wish to change to using the Texas Department of Public Safety's online guide (see Resources). For example, federal law dictates that a class A license is required for any combination of vehicles with a gross weight vehicle rating (GWVR) of 26,001 lbs. or more, provided that at least one trailer has a GWVR above 10,000 lbs. Class B licenses are required for single CMVs that weigh 26,001 lbs. or more. Finally, class C licenses are required in Texas for vehicles that weigh less than 26,000 lbs. and either require HazMat placards; or are designed to transport 16 or more passengers (including the driver).
Determine if you require to change your CDL to add any endorsements. CDL endorsements are determined by federal law and required for certain types of vehicles. You must complete further testing to gain endorsements, with each endorsement costing $11 (as of March 2011). For example, to obtain a class P endorsement, which enables motorists to operate a passenger vehicle, drivers must pass both a knowledge and skills test. To gain a class T endorsement, which enables motorists to operate a vehicle with a double or triple trailer, drivers are only required to pass a knowledge test.
Find your most convenient DMV office (see Resources). Inform it of the change you wish to make; for example, you might want to change your class A license to a class C. Present all documentation required, which includes your current CDL, proof of Texas residence, Social Security card and insurance documents for the relevant vehicles (both the vehicle you used to drive and the vehicle you wish to drive with your changed CDL). Ask about any examinations you are required to take --- you do not need to retest when making any change between class A, B or C licenses in the state of Texas. Book yourself in for any required examinations.
Learn the Texas commercial motor vehicle drivers handbook (see Resources) before taking any additional tests. Read through the entire handbook and get your family, friends or colleagues to help you learn the material. Everything you require to pass any endorsement examination is contained within the Texas commercial motor vehicle driver's handbook.
Take your examination at the designated center --- this is almost always the DMV office itself. Carry out any practical testing, where you will be accompanied by an examiner in the cab of the CMV that you are taking the test in. For example, if you are looking to obtain your class S endorsement, which enables you to drive school buses, you will be joined by an examiner as you drive a school bus. Complete all three stages of any practical test: the pre-trip inspection, maneuvers test and road test.
Visit the DMV office, pay for and collect your changed CDL.
