[tomp]

It's hard to tell from the pic, so gotta ask is the tire hitting the frame of the tire carrier? This depends on your wheel offset, so that may be why it's vibrating. If it's not, consider cutting/welding the brace until the tire will flush up against the tire carrier frame. I am gonna have to do this myself.

It's a good idea because you will find that most small trailer jacks will hit the tire before they mate to the hitch.

Mine vibrates going down the road as well and it sags too!

I actually had to palce washers on the wheel studs to keep the wheel from pulling up against the studs too far. Once I needed the spare, it was stuck on there and would not come off without beating the wheel studs out of the carrier.

Also, if you tow, you might want to check my posts on towing and having spare get in the way.