As part of the Association of American Railroads’ (AAR) Strategic Research Initiatives (SRI) program, MxV Rail has been investigating the root cause (or causes) of asymmetrically hollow worn wheels. Results from a 2022 MxV Rail investigation eliminated some potential root cause(s) and were reported in an earlier Technology Digest.1 However, another study2 from 2010 found that the brake system’s linkage layout was the root cause for asymmetric wheel wear on a coal fleet. There is an ongoing effort at MxV Rail to determine the root cause(s) of asymmetric wheel wear on cars other than the coal hopper fleet studied in the past. MxV Rail researchers are continuing their root cause identification effort and have performed a study of wheel wear data of trucks only having one of the two wheelsets replaced within a truck, or single wheelset changeout, to determine the influence the worn wheelset remaining in the truck might…