Product review (5 stars): They did the trick
I have a Whirlpool Duet front loader that rests on a travertine tile floor in a ground floor laundry room. This washer has always walked with a heavy load spinning in the drum but it got worse when we replaced the linoleum with tile. I tried to solve the problem by leveling the washer but that only made the walking more pronounced. I suspected that the hard plastic feet on the washer were sliding on the tile floor.  I used a search engine to find rubber feet for appliances and found the Anti-Walk Silent Feet listed among the results. The Silent Feet pads seem pricy for what you get but I was tired of repositioning my washer after every other wash load. I'm happy to report that the pads worked. I ran a load of the usual problem items -- denim jeans -- and the washer remained in place.