I've 'sussed' the driving rules . . .

Each 24 hours must have a 10 hour continuous 'rest' period (leaving 14 hours - during which 11 can be driven).
After 4 continuous 14 / 11 hour days only 4 further hours can be worked (total 60 hours). If daily driving is less than 11 then 60 hours in 7 days or 70 hours in 8 days is allowed.
After 60 (or 70) hours duty a 24 hour period and a 10 hour rest period must be taken before driving can resume.
If driving only - maximum 11 hours per day (no non-driving hours) then after 5 days a further 5 hours can be worked before a 'weekend' (24+10 hours) must be taken.
As far as I can tell this effectively means 5 days with one hour per day 'not driving' then a 'weekend'.
Anybody got any better combinations?

There’s no federal road tax, although all states levy an annual registration fee, which varies considerably from state to state.

Motor vehicle registration rules and fees vary from state to state. The registration fee may be a flat fee or be based on a vehicles weight, age or value (or a combination). Upon registration, you’re issued with one (affixed to the rear of a vehicle) or two licence plates, the expiry date (month/year) of which is shown on the rear plate. A variety of personalised plates are available in most states (for an extra cost) and all states provide special plates for the disabled (a medical certificate is required).

Registration fees are usually paid annually, on a fixed date for all owners, or more often staggered, often based on your birthday or the first letter of your family name. There are usually penalties for late renewal and you can be arrested for displaying an out of date (dead) plate, although some states allow a grace period. Registration is validated by a sticker affixed to the rear registration plate. Duplicate plates and registration papers are available for a small fee.

http://www.truckinfo.net/trucking/li...-per-state.htm

http://www.justlanded.com/english/US...ving-in-the-US

http://www.worldlicenceplates.com/usa/US_XLPR.html

Does that mean that plates on tractors are hidden by the trailer?
Will this guy need plates for each state?

http://www.ador.state.al.us/motorveh...les/51204.html

Click on the link at the bottom of the above page for all the rules - good luck

Re - Interstate plates

http://www.alsea.org/News/ADOR_Announcement.htm

Licence plates in Denmark are issued when a vehicle ownership changes, so it's difficult to tell the age of a vehicle from its plates unless it has remained owned by the original owner.
If the annual fee is not paid or if no valid insurance then the 'Traffic Police' come round and remove the licence plates - it's as simple as that . . .

http://www.worldlicenseplates.com/

This link shows what the plates look like