Check for a tire out of round or a balance problem first. And yes, go over everything with a wrench to make sure everything is tight also. Mine came completely assembled by weak, broke back mountain Chinese that couldn't pull a wrench.
Will do..... Blows my mind that you pay all this money and you have to tighten things up after 60 miles on the odometer
If you only knew how loose things are put together, you would have put a wrench to as many nuts and bolts as you could before you did the first 75 miles. Scary!! Retighten bolts like the windshield mounting bolts under the rubber plugs, to all suspension, steering and brake bolts and nuts. Body mount bolts and nuts. If it has a nut or bolt and you can reach it, give it a twist. I have found the ones on the engine and trans to be fairly tight. It's mainly the body bolts and nuts that are loose. Make sure you go over all the rollbar nuts and bolts. Also check the differental nuts and bolts that mount it to the frame front and rear. Get out your wrenches, get your best buddy to help and buy a twelve pack and have tightning party in the driveway.
Yes to low can do this as well. Also the track seems to be slightly less then the average road ruts and with to low of pressure you can feel the effects more of the tread wanting to follow in the pavement ruts. I run mine at 14 psi, but I have 3 ply sidewalls. I do feel more squirming on some roads with decent road ruts.