For the rear you can use a wood rasp to shave off the cupping. Not sure if it is a rasp or file, but you put bike on centerstand and run it in gear. With tire turning, rest the rasp/file on tire and shavings will fall off like butter. Just make sure you hold the tool with your hand at the bottom just in case the tool grabs the tire. Safety safety.
Any ideas how to do the front tire? I brought this up a few years ago but the old info is gone and I never did do that tire, replaced it instead after another 1200 miles.