[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR229.73] [Page 316] TITLE 49--TRANSPORTATION CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 229--RAILROAD LOCOMOTIVE SAFETY STANDARDS--Table of Contents Subpart C--Safety Requirements Sec. 229.73 Wheel sets. (a) The variation in the circumference of wheels on the same axle may not exceed \1/4\ inch (two tape sizes) when applied or turned. (b) The maximum variation in the diameter between any two wheel sets in a three-powered-axle truck may not exceed \3/4\ inch, except that when shims are used at the journal box springs to compensate for wheel diameter variation, the maximum variation may not exceed 1\1/4\ inch. The maximum variation in the diameter between any two wheel sets on different trucks on a locomotive that has three-powered-axle trucks may not exceed 1\1/4\ inch. The diameter of a wheel set is the average diameter of the two wheels on an axle. (c) On standard gauge locomotives, the distance between the inside gauge of the flanges on non-wide flange wheels may not be less than 53 inches or more than 53\1/2\ inches. The distance between the inside gauge of the flanges on wide flange wheels may not be less than 53 inches or more than 53\1/4\ inches. (d) The distance back to back of flanges of wheels mounted on the same axle shall not vary more than \1/4\ inch.