Getting to the main tinanjas involves various stages of readiness. To use the old ore rd, a high clearance vehicle is best. (you don't need 4-wheel drive)
Once you get to the parking area, you have a nice easy walk to the tinajas, with only slight elevation changes.
It becomes a level 4 or 5 difficulty if you decide you want to cross the main the tinaja. I have gone THROUGH the tinaja (when super shallow) and climbed the wall of rocks. I have went up and over on the left side and up and over on the right side. Either will take guts and balance. Be super careful. Coming back stay on the right side (as you are facing OUT towards parking lot) and go about halfway, then slide down the smooth rocks on your bottom. Have someone there to catch you.
It's a great hike and spectacular colors in the rocks to see.