Consider the centripetal force. There will be two forces acting on the vehicle: the normal force of the road, since the curve is inclined toward the center of the curve, and the static friction force from the traction of the wheels.
Since there is only acceleration in the radial direction, the forces in the direction perpendicular to the radial direction cancel one another:
Solving for m in the second equation and substituting it into the first, you get:
Finally, solve for v, which will give you two different solutions. These are the minimum and maximum speeds required for the vehicle to remain on the curve. Notice that m cancels out. This is because all the forces involved, gravity, friction, and normal force, act relative to the mass of the vehicle.