49 CFR § 229.73 - Wheel sets.

---
identifier: "/us/cfr/t49/s229.73"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 229.73 - Wheel sets."
title_number: 49
title_name: "Transportation"
section_number: "229.73"
section_name: "Wheel sets."
chapter_name: "FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
part_number: "229"
part_name: "RAILROAD LOCOMOTIVE SAFETY STANDARDS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 20103, 20107, 20133, 20137-38, 20143, 20168, 20701-03, 21301-02, 21304; 28 U.S.C. 2461 note; and 49 CFR 1.89."
regulatory_source: "45 FR 21109, Mar. 31, 1980, unless otherwise noted."
cfr_part: "229"
---


# 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.