This is not legal in California. If you are a resident in California you need California plates/registration. Even if you're a non-resident you need to register it here within a short period of time.
> Except as provided in Section 6700, 6702, and 6703, any vehicle which is registered to a nonresident owner, and which is based in California or primarily used on California highways, shall be registered in California.
> Except as provided in Section 6700, 6702, and 6703, any vehicle which is registered to a nonresident owner, and which is based in California or primarily used on California highways, shall be registered in California.