good luck washing semi's. Been there done that what a PITA.
Yes HF or ABF is the go to chemical for the chrome but it will streak and white out aluminum like crazy. Even a chemical on the high end of the pH scale will streak the aluminum. Many degreasers fall into this category so you have to be really careful otherwise you'll streak the aluminum and you'll spend all day trying to polish it back to halfway decent looking. I've made this mistake before.
In my opinion you'll never make these big rig customers happy with power washing. You're going to want to offer power washing and they're going to want to receive detailing. Two different animals.
there are a lot of better businesses to go into then pressure washing. consider this fact: If you are not containing, collecting and properly disposing of your wash water you are in direct violation of the federal clean waters act. I suggest you look up that law and become very familiar with it before you get too far into a pressure washing business. Federal law does not allow any
soap, chemical, surfactant, etc. to drain onto the ground because according to federal law you are contaminating the ground water by doing this.
I'm not just trying to scare you. I learned this the hard way believe me. All it takes is one neighbor to complain and the EPA will issue a cease and desist order. That's what happened to me years ago. in an instant, my days of power washing vehicles outdoors came to a screeching halt. I wasn't about to buy a containment mat, suck up all the water into a holding tank, and then pay a septic hauler to truck it away. You'll find that to be very cost prohibitive. you might say to yourself oh I've seen several power washing companies in business and none of them do this. That may be true, however they all are in violation of the federal clean water's act and all it takes is one single complaint like I said earlier.
consider the following story from a local bus company. They had a set up to wash buses on their property. Someone dropped a dime to the EPA. The EPA came out and issued a cease and desist order to the bus company. The bus company played nice for a while and then went back to their old ways of pressure washing buses Without properly disposing of the wash water. The EPA found out about it. They sat outside and watched them washing buses. After the first bus,They came and issued a $10,000 fine. The bus company was furious. The EPA inspector said "well I could've let you wash all the buses you had in the queue and then issued the fine At a cost of $10,000 per bus".
I speak from experience but I wish him luck.