You could start your own mobile tire installation service business, and be in business for yourself! You could offer your service, by contacting certain tire dealers, in your neighborhood. Talk to them, and let them know, you want to start your own business, and you would like to get a discount on tires from them, if you become a regular customer for them, and better them, than their competition, up the street.
Tires stores are just about everywhere these days! Everyone needs tires eventually, just no way around it, and that is good for you! It is a hassle, for most people to take their car to a tire dealer, wait sometimes forever, if they are busy, and then get shoddy service, and hidden extra charges, almost all the time.
If you take that worry away from your customer, you will do good! If your customer had to pay $500 for a set of tires from the same dealer you just made a deal with, to get them, say, for example, $400, you would make an instant $100 profit on that, and then if you install them, and charge another $100 for that, you could make $200, in just one or two hours time! Walk around any neighborhood, and look at the cars you see in the driveways, or on the road. You could go threw any parking lot in America, and look at the tires on cars as you walk around. The cars with the bald tires will be your best customers!
Let them know you will take care of everything. In the beginning, you can come to their house, put their car up on jacks, take the tires to the tire dealer, have them put the new tires on, and take them back, and install them, back on their car, and your customer will be happy, that they did not even have to leave the house!
You could later, after you get more experience, and a better truck, you could get your own tire machine, and do the tires yourself, right in the back of your truck, and pick the tires up ahead of time, for your customer, so their car, is not up on stands for too long. You would want to have signs made up for your vehicle, and pass out business cards to all the cars you see with bald tires!