Hey guys, I hate to ask a question thats already been asked and answered but I searched for this to no avail..
Yesterday my brother happened to be driving behind me while I was on the bike. He mentioned later that the back wheel looked like it was wobbling, or was 'loose' as he called it. I went for a ride with a buddy that evening and told him to keep an eye on it and he said the same thing. However, it seems that it's only noticeable at slower speeds. I don't have too much experience with driving bikes and ive only had this one on the road for a week or so. In other words, I can't tell if it feels loose or wobbly or not.
I don't want to screw around with it too much in case I make it worse but what is most likely causing this? Is the wheel not seated in the frame properly? Should I try jacking it up and adjusting the two smaller bolts on either side of the wheel? Any info or advice is greatly appreciated.

I once had a car tire with broken belts, and it wobbled like crazy at lower speed. Don't know if your tire has belts in it, but I'd suspect the tire until proven otherwise.

Look carefully at the line where the tire is seated in the rim. One section may not have seated fully, thatll make one look to be wobbling.

see if your spokes are in tune