Over time I have purchased several different size Wire Nails or Brads at Home Depot to use for mounting wheels on a model. From the most used size, #15x1 1/2, #16x1 1/4 and #17x3/4 length. I even have some #18x3/4 but haven't had to use them that often. They come in small plastic containers and are usually sold based on weight, so they are really inexpensive. You will need a large wire cutter type of plyers to cut to length.