I run my street tires with no foam and havent had an issue or weird sound yet

 

Ring simply dampens squealing if there should be any. Might even dampen noise that may not be clearly audible for EPA./DOT noise regulation, after all noise is noise regardless of where it comes from. Years ago Harley had to have extremely muffled bikes because there was so much engine noise, it was near the limit on noise regulations. Later, with newer engines that became less an issue. Same thing with air boxes, the snorkels may be partly due to intake noise. They do what they have to do to pass regulations.

To the OP....
Now go play in some open fields with minimal hills and get a feel for the bike. Worst most dangerous thing you can do is try riding situations you are possibly not prepared for. Worst thing many new riders try are hill climbs. Personally I avoid them. Why should I be trying to go up some place where, if I don't make it, my bike will posslbly bounce to the bottom breaking stuff? Just didn't make sense to me. As a trials rider I would drop off and go down almost any hill, I also knew most hill climbers won't come back down that steep climb, so I'd find their easy route down, go to the top and ride down to see what the hill was like.

Do the easy stuff and have some fun. Try sliding the back end out a bit. Practice braking, try to use the front brake with a couple fingers, so you can release it while still having a grip on the bars. I use my front brake at least a little in probably 95% of my braking on or off road. Only time I may not touch it is in slippery mud or similar stuff. I at least have a touch on the lever. Try pulling the front wheel standing up, using a bit of throttle and a tug, the kind of thing required to go over a log or rock on a trail. Play around a lot. Set up or figure out some courses where you can practice looking where you want to go. Maybe set up some stuff to create a path where you must pick exactly where you want the front wheel to track. Get used to looking exactly where you want to go. You will go where you look. Look up the path thinking where you're going, the as you ride on think about it - did you go exaclty where you looked?

I practice this on the street several ways. Coming to a stop exactly on a spot in the pavement I targeted. When riding where theie is no traffic I ride between the two yellow lines, looking up the road between them. I see a pot hole I look just off to the side and go past it. I weave between the dotted lines when there's no traffic. On dirt/ gravel I see bumps and ride where I want to over or around them. You look ahead to track where you want to go. You don't look at your feet a you walk or run, you look ahead, same with the bike. Just start out doing it where you have lots of run off. You have plenty of time to eventually tackle the tough stuff, give yourself that time to learn.

Besides, its cheaper because you don't break as much stuff.

Then hit the trails, but do easy ones to start. Think as you ride, if you drop down over a hill can you get back out? Does a path look like it's going to be trouble? Have you figured out your path in those tough spots? Have you learned to look where you want to go?

 

Learn to ride and operate / slip the clutch while going down/up the trail. If your bike starts going real slow, start slipping the clutch before you fall down. .... it takes practice.
Until you have experience, do not try and pull a wheelie over anything. These bikes don't have that much power.

 

I have a rear fender cover if you need one. Left side. Same camo color. Has some light scratches on it but not noticeable esp if yours are cracked. Ride on!