[Seany (OP)]

Will it be able to NOT roll down a slope of 45 degrees?.. Or do all spheres and circles, which have a tangent, have to roll, no matter the mass?

[another_someone]

Assuming they have enough mass, and sufficient gradient, to overcome stiction (which depends on the materials there surface is made from, not anything to do with mass), then any perfectly spherical will inevitably roll down even the smallest of gradients.

[lyner]

If it has mass and the Earth has mass, too, then there will be a force of attraction. If the opposing forces - friction  or a rope - aren't as great as this, then the two will move together.
Seany, you do pick some whacky questions - keep 'em coming.

Will it be able to NOT roll

Are you suggesting that, if it were heavy enough, it might sink into the road, rather than roll down? The answer to that is yes. It happens all the time. Cars are constantly getting bogged down on muddy slopes.