There are different kinds of tires for your bike. Fat with groves and thin without. How is a person supposed to know which kind of tires they need for their bike? It's all so confusing and no one ever told you about bike tires. Your parents bought you a bike and assumed that the tires on them were the right kind of tires for you. Why wouldn't they think this? The bike store or bike manufacturer should have known. So you why should you have to give it a second thought? Right?
Well, unless you told the bike shop owner what you are going to do with the bike how is he supposed to know which tires are right for you. If you bought your bike somewhere other than a bike store than you are stuck with whatever tires the bike comes with.
I found out the hard way that a mountain bike is not good for on the road. When I went on my first road ride with my cycling club I took my mountain bike. My idea was that with the extra gears I would be able to do the hills easier. Boy was I wrong. I found out after the ride that mountain bikes make it harder to get up the hills on a road because of the tires and because the weight of the bike is so much higher than the weight of a road bike.
I struggled for the whole ride. Then I got a different bike. My next ride was much easier and all because I changed to a road bike. Tires do make a big difference to make sure you find out what kind of tires you need and get them.