[tmerc]

Unless your car is very new, you have all the stuff you need to learn to change a tire in the trunk. Watch 2 short YouTube videos and go do it. It'll take you half an hour. You should use a torque wrench but if it was that critical, one would be in your trunk.

After that, look up your maintenance schedule, pick a job, then go figure out if you can.

When you get into bigger jobs, have a tow company and shop ready in case you run into problems. Mobile mechanics may also be an option.