When you have a tire that is cupping, there is a temporary remedy.
The uneven wear can be smoothed with a body grinder.
Just spin the wheel and grind as it rotates, {cut at a 45* angle so the grinder rotates the wheel as it cuts}.
Take your time and you can remove the high sections.
With a little practice, (and if you don't wait too long before doing it) it can improve the ride and get more miles out of the tire.
NOTE: This is a temporary fix. But it will give you more time on the tire.
Yes, I know your removing rubber, so (you may think) tire life is being decreased.
But, your removing it from the thicker side area of the tire,,, not the center.
And, if the tire is so bad your going to get ride of the tire, why not extend it a little until you new tire arrives?
Ride safe, Ted