Helmets off-road
RCW 46.09.470 makes it a traffic infraction to operate or ride an off-road vehicle on a nonhighway road without wearing a motorcycle helmet fastened securely while in motion.
That fastened-securely language appears in the street helmet law too and is worth taking literally. An unbuckled helmet is a helmet that leaves your head at the first impact, which is the moment it was supposed to be doing its job.
Under 16 needs supervision
RCW 46.09.460 requires riders under 16 to be under the direct supervision of a licensed adult 18 or older.
Direct supervision means present and supervising, not somewhere on the same property. This is the provision that governs the very common situation of a young rider on a trail bike with a parent nearby.
Off-road does not mean unlicensed on the street
The most consequential misunderstanding here is riders assuming that competence off-road, or an ORV decal, translates to street legality. It does not.
An off-road motorcycle ridden on a public highway needs to be converted, inspected, declared and registered, and the rider needs a motorcycle endorsement like anyone else. The full process is in making a dirt bike street legal.
Riding an unconverted dirt bike on the road is not a technicality. It is an unregistered, uninsured vehicle plus, usually, an unendorsed rider.
What dirt teaches, and what it does not
Off-road riding builds genuinely valuable skills. Throttle control on loose surfaces, comfort with the bike moving underneath you, and recovering from a slide are things street riders often never learn, and they transfer well when a wet Washington road goes slippery.
What it does not build is traffic craft. Reading driver intent, lane positioning for visibility, intersection strategy and emergency braking on tarmac are separate skills, learned separately. Riders who arrive from dirt are often the most capable people on the range at controlling a motorcycle and the least practised at anticipating a car.
That combination is worth knowing about yourself, because confidence in one domain reads internally like confidence in the other.