The Joshua Tree OHV trails are located in Washington County, Utah at the north end of Gunlock State Park. There is a place to stage at the trailhead, parking in the town of Gunlock or you can ride right out of Gunlock State Park if you are staying there.
This trail is about 55 miles of graded road and some two-track through the desert. We spent 5 hours at an average speed of 10 mph riding. You can easily make this a full day trip taking some of the side roads exploring this remote corner of the state.
There are no services on the trail but you will drive right through St. George and Santa Clara to the trail so stock up on anything you need there.
Riding would be generalized as easy going graded sandy roads with plenty of dust (this is the desert) and you will see Joshua trees.