I am new to the whole Jeep thing but was looking for some imput. When i get on the highway i get a vibration through the Jeep. Its only from about 50-70MPH. I dont feel it in the steering wheel or the brake pedal. What else could it be? Its a 2002 Sahara 5spd and has the stock 30" tires. They were just replaced about 3k miles ago.