很多州車轉手後老車牌就廢了，比如加州10天你你的去拿新牌

As a general rule, you must obtain new registration plates within 10 days from the date of purchase of a new or used vehicle. If you are applying for a car tag after purchasing a vehicle from a private party, you must visit a local DMV office and complete the application process in person. Furthermore, when applying for CA car registration tags, you must submit the vehicle title, a bill of sale (if applicable), an odometer mileage disclosure (if the vehicle is younger than 10 years of age), a smog certification (if applicable) and an acceptable payment method for any registration and license plate fees.