Google Where can you get a tractor trailer to take a CDL road test?

Answer 1

Before you even get into a commercial vehicle, you must have the appropriate learner's permit (if you're upgrading from a Class C license to a Class A license, it would denoted usually as "CPA"). Without that, you can more or less forget about it.

Once that is done, you would either need to find a company which is training you to work for them to either provide a vehicle or - if they have the state's approval to serve as in independent testing facility - test you themselves. This typically requires you to enroll in their driving school, however.

Or you could enroll in a driving school at your local community college.

No rental company is going to rent a truck to you unless you have your CDL already. If you can find a CDL licensed driver to actually rent the vehicle, and drive it to the DMV testing facility, it may be possible, provided that your state actually has a facility available - again, this is usually carried out by third party testers.

So, in a nutshell, enrolling in a driving school is really your only feasible option.