My rear tire is ever so slightly loose - two millimeters at most, but noticeable.
I experience this when I apply pressure at the top of the tire, like so:
From the other side, there's no looseness at all.
It's a 6-7 year old bicycle that has never been serviced. I suspect I need to change something, but need your advice on what that would likely be.
Is it only the tire or the wheel itself that is lose? I am guessing you mean the latter. Check by grabbing the top of the entire wheel and try to move it/rattle it left/right. Does it rattle?
Make sure the quick relase is properly tightened by releasing the QR, making sure the axle sits properly in the drop out and retighten it. If the problem is still there, remove the wheel from he bike and check if the axle has play (you can wiggle it/it rattles).
If it has play you need to service the hub which might save it (by retightening cone/replace bearings, broken axle?), but considering the wheel's age it might also be worn out in which case the only cure is to replace the wheel.
If the axle has play, the axle itself might be broken. This is inexpensive to fix, although you might want to let a bike shop do the work.
