Unlike a car, it's not always possible to adjust motorcycle mirrors without a wrench. That's why you want to check their positioning before you start riding. It's simple. Just get on the bike in riding position and check that the mirrors are where you need them to be able to see as much as you can around you. If your bike has a center stand, this is especially easy to do while it's sitting on the center stand. If not, get on the bike and point it straight ahead. Hold the front brake lever if you're on a downhill incline. Adjust as necessary.