Experienced a constant lateral vibration from front end at speeds greater than 50 mph while pressing gas pedal. This occurred after taking 600 mile road trip, made it 600 miles back home, vibrating all the while. Had my mechanic look at it, replaced front tires. Later that week, while entering highway on ramp, punched the accelerator a bit harder than normal and heard a shredding sound and battery light came on. Serpentine belt was shredded. Made it to a shop along the hwy on remaining battery power. They told me it was the belt tensioner all along not the tires.