- Decent tires on all four wheels
- Decent spare (preferably full size)
- Tools to change a tire (and the know how to do so!)
- Tire repair kit (and the know how to use it)
- Tire pump
These Amazon affiliate links are to the exact items I bought, chosen based on customer reviews/ratings. Fortunately, we didn't have a need for either on our trip but they now live in my car and I sure feel better being prepared for a flat!