One night about a week ago, i got me a pair of splash guards to put on my GN so i wouldnt continue to chip the paint from my excessively wide drag radials. I got the left rear tire off, and just taped the guard on to see how it would look. Talk about ghetto. So i ditched the idea real quick like. I put the wheel back on and went for a test drive just to make sure it was all good. It wasnt. It vibrated a little once i hit 55. I check all my u joints and everything. Everything was damn tight. So i took my wheel back off and made sure i torqued it down perfectly. Checked all the air pressure on the tires and filled them up accordingly. It seemed better after doing this, but it still seemed to a little. The roads around here are pretty damn bumpy and i am pretty paranoid about my car. If anyone could tell me what it might be, itd be much appreciated.