The article on "Building A Gondola Load Of Wheels" by Bob Kale (See: https://groups.yahoo.com/neo/groups/Model_Railroads_Of_Southern_California/conversations/messages/11431) got me to thinking about doing something similar.
I had a vintage HO scale Revell gondola with a simulated gravel load stuck almost out of sight on the layout. When I say vintage, this car was first produced in 1956 and I bought it new, still in the original box in the early 1970s. Had it been more accessible I probably would have sold it with the other 100-plus older, less detailed freight cars I parted with over the past few months.
So this car was given a second chance at life with a coat of Dullcote, several oil paint washes, more Dullcote, Vallejo rust washes selectively applied, more Dullcote and finally PanPastel colors selectively applied. The truck frames and wheels also were painted/weathered and the journals received Teflon lubricant.
I had a good supply of plastic wheels from converting several hundred freight cars to metal wheels over the past fifty years. These were ok for the bulk of the scrap wheel load but they were generally too thick and lacked a true prototype look. To the rescue came some non-functional Tichy wheels. These are made for the Tichy wheel car (http://www.railroad-line.com/forum/data/desertdrover/2011122615511_WheelCar02.jpg) but the wheels also are sold separately as Part Number 3004.
The wheels received a coat of Krylon Red Oxide Primer followed by painting some of the individual wheels with one or more of the following:
Vallejo Rust Washes
AK Interactive Crusted Rust Deposits (See Photo)
Poly Scale Rust
Model Master Rust
The simple objective was to not have all the wheels look the same.
I secured the wheels a few at a time to a piece of scrap styrene with Canopy Glue. The better Tichy wheels were distributed along the top row of wheels.