I have been through this a couple times in AZ with my bigger trucks and Bartamos has the right idea. The yearly registration fee depends on on what GVW you claim. A heavier truck is more expensive. They are doing you a favor by asking what weight you want to claim. The first time I dealt with this was with my Diamond T which has a GVW of 14,700. The gal asked me what I wanted to claim and I said the truck has a GVW of 14,700 and she repeated "What weight do you want to register it as" and I responded again 14,700. Once again, and very slowly with an eye roll and a smirk, she repeated her question. Then the light bulb went on and I said 8,000 (empty weight of truck is 6500) and that is what she put down.
Occasionally, I take a trip to the dump and probably exceed the weight but around here I have never heard of anybody being hassled about weight when driving an antique truck. In 16 years I have put only 3k miles on that particular truck and most often I am empty so it is not an issue (and the State benefits by charging me for a commercial vehicle that sits most of the time and doesn't wear out the roads).
