Texas HOS if registered outside of Texas

Where your truck is registered doesn't matter, as long as its registered. If you are based in Tx and are operating intrastate in Tx, then you operate on the hours of service regulations in Texas. If at any point, you leave Tx, you are subject to the federal guidelines. Keep in mind that if you start a trip in Tx destined for another state, then that trip would likely be considered interstate in nature and the entire trip regulated by the federal guidelines. When determining whether a trip is interstate or intrastate, we look at the INTENT of the trip. So you may still be in Tx, but operating on an interstate journey. But a trip that starts in Tx and ends in Tx is intrastate and only subject to the rules in Tx. What state you are registered in, doesn't matter as long as you are legally apportioned to operate in whatever state you enter.

 

And the expand a little on the above..
Trip is a little misleading. If any time thst load has or is intended to leave the state, that run is interstate. The load has to be 100% in Texas, not just the driver.

For example:
Pickup sand in Waco, and deliver to an oil patch in Lubbock. That's Texas HOS as the load doesn't leave the state.
Pickup a container in Laredo that came from Mexaco and deliver to Dallas. That's interstate, federal hos. Sure the driver never left the state, but the load did.