If they can't solve the vibration by balancing tires somethings wrong. Also, a car sitting for 2 months might have a flat spot but shouldn't cause a balancing issue. The tires stayed on the same place on the rim and i'm sure someone has driven it. I think the tire balance things is bs. Either way it should have a full warranty but remember warranties don't cover brakes and tires. If it's a balance issue it will do it every time at a certain speed. If that's not the case something else is wrong. Sorry