Product review (5 stars): More uses than dishwasher racks
I didn't buy these for dishwasher rack tips; I bought them for covering the ends of brake bleeder screws to keep dirt and moisture out.  They work better than the caps sold as brake bleeder caps and are much, much cheaper.  FYI the inner diameter is 1/8 inch easy slide on and off but if warmed up they can be made to fit as big as 3/16 inch.