I had this happen once after a pothole, turns out the impact knocked loose some of the wheel weights, so they needed to be rebalanced.

There are 7273627 different things that could be happening, but check for this too

What do you mean at the roadside? Like can you replace it on the shoulder of the road?

What car is it? You might be able to pick one up at autozone or similar for cheap if it’s a common car.