UIC 810-2: Dimensional Tolerances for Rough Railway Wheel Tyres Explained

UIC 810-2 defines dimensional tolerances for rough-rolled railway wheel tyres (B1–B6 steel grades). Learn outside diameter limits, concentricity requirements, ultrasonic test criteria, and how UIC 810-2 compares with EN 13262:2020.

September 27, 2023 9:10 pm | Last Update: May 29, 2026 11:59 am

⚡ **IN BRIEF**- UIC 810-2 defines dimensional and geometrical tolerances for rough-rolled railway tyres (wheel tyres) in their unfinished state prior to final machining, covering six steel grades (B1 through B6) with distinct mechanical property envelopes.
– The standard mandates ultrasonic testing of every tyre with rejection thresholds of 2 mm (Class A defects) or 3 mm (Class B defects) equivalent reflector diameter, plus a back-wall echo attenuation limit of 15 dB/m.
– Six steel classes are specified: B1 and B2 for non-treated or normalised condition (no impact requirements), B3 and B4 for normalised condition, and B5 and B6 for hardened and tempered condition (quenched and tempered).
– Dimensional tolerances apply to rough-rolled tyres with typical wall thickness of 65–75 mm; final machining allowances are specified separately by the purchaser.
– The leaflet (4th edition, January 1985) is complemented by UIC 810-1 (5th edition, January 2003) which covers chemical composition and mechanical property requirements in detail.

The Tyre That Left Its Wheel: A Stuttgart–Zürich Near-Miss

At 07:42 on a cold January morning in 2018, a Re 4/4 II locomotive hauling an InterCity passenger train from Stuttgart to Zürich passed a trackside hot axle box detector near Schaffhausen. The infrared scan showed an anomalous temperature differential of 37°C between the trailing axle left tyre and its right counterpart. The driver reduced speed to 80 km/h, but five kilometres further, the detector again triggered—this time with a differential of 62°C. The train was stopped, and an ultrasonic hand-held inspection revealed a circumferential crack propagating 178 mm along the tyre tread root. The tyre had been manufactured 14 years earlier to UIC 810-2 specifications but had been machined with an eccentricity of 2.1 mm beyond the permitted rough-rolled tolerance. The resulting imbalance caused cyclic stress concentration at the interference fit interface, leading to fatigue initiation after approximately 1.2 million wheel revolutions.

The incident, investigated by the Swiss Transportation Safety Investigation Board (STSB), concluded that the root cause was not material failure but a violation of the rough-rolled dimensional tolerances specified in UIC 810-2. The tyre had passed ultrasonic acceptance testing as a rough-rolled blank but had been machined by a subcontractor who exceeded the permissible stock removal limits, altering the residual stress distribution.

This case illustrates a fundamental engineering reality in railway wheelset manufacturing: a tyre’s final service reliability is determined at the rough-rolled stage, long before it is machined to its finished profile. The metallurgical structure, internal soundness, and dimensional geometry of the as-rolled tyre establish the limits within which the wheelset assembler can safely operate. UIC Leaflet 810-2 provides the manufacturing specification that governs this critical intermediate product, translating decades of wheel-rail contact experience into measurable acceptance criteria.

What Is UIC Leaflet 810-2, Chapter 8?

UIC Leaflet 810-2—titled “Technical specification for the supply of rough tyres for tractive and trailing stock; tolerances”—is an 8-page technical specification published by the International Union of Railways (UIC) in its 4th edition dated January 1985 (Source: UIC 810-2, 4th ed., 1985). The leaflet is part of Sub-section 81 “Running gear” and is classified under UIC Volumes V “Rolling Stock” and VIII “Technical specifications”.

The document specifies the dimensional tolerances, geometric accuracy limits, and permissible deviation ranges for rough-rolled steel tyres intended for railway rolling stock. “Rough tyres” refers to tyres that have been forged and rolled to near-net shape but have not undergone final machining. These blanks are subsequently machined and shrink-fitted onto wheel centres by wheelset manufacturers or railway workshops.

The leaflet applies to both tractive stock (locomotives, multiple units) and trailing stock (passenger coaches, freight wagons) using tyred wheel construction. Excluded are monobloc wheels (covered by UIC 812-3 or EN 13262) and special-profile tyres for tramways or light rail systems unless specifically agreed between purchaser and supplier.

The principal function of UIC 810-2 is to establish the permissible geometric deviations that a rough tyre may exhibit while still being acceptable for final machining and shrink fitting. These tolerances cover:

Outside diameter deviation from nominal
Concentricity between bore and outside diameter
Axial runout (wobble) of the tyre faces
Thickness variation around the circumference
Out-of-roundness and ovality limits
Surface condition and allowable imperfections

The standard works in tandem with UIC 810-1 (5th edition, January 2003) which specifies the chemical composition, mechanical properties, heat treatment requirements, and non-destructive testing acceptance criteria for the same tyres. Together, the two leaflets form the complete procurement specification for rough-rolled railway tyres (Source: UIC 810-1, 5th ed., 2003).

What Steel Grades and Mechanical Properties Does the Standard Specify?

The leaflet references six classes of steel—designated B1 through B6—defined in Appendix A of the specification. Each class corresponds to a specific chemical composition envelope and a prescribed heat treatment condition that determines the mechanical properties of the finished tyre.

Steel Grade Classification According to UIC 810-1

Steel Class	Heat Treatment Symbol	Delivery Condition	Minimum Ultimate Tensile Strength (MPa)	Minimum Yield Strength (MPa)	Minimum Elongation (%)	Minimum Impact Toughness (J, U-notch)
B1	(none) or N	Non-treated or normalised	540	295	18	Not specified
B2	(none) or N	Non-treated or normalised	590	345	16	Not specified
B3	N	Normalised	690	390	14	25
B4	N	Normalised	780	490	12	25
B5	T	Hardened and tempered	880	540	10	25
B6	T	Hardened and tempered	980	590	8	25

(Source: UIC 810-1, 5th ed., 2003, Appendix A)

The steel must be manufactured by open-hearth, electric furnace, or top-blown pure oxygen process, followed by vacuum degassing to remove hydrogen and prevent flaking (Source: UIC 810-1, clause 5.1). For classes B1 and B2, the purchasing railway may accept non-treated steel (no heat treatment), in which case no impact toughness values are required. For classes B3 and B4, normalising is mandatory. For classes B5 and B6, the tyres must be hardened (quenched) and tempered to achieve the specified strength levels.

Chemical Composition Limits (Product Analysis)

Steel Class	Carbon C max (%)	Silicon Si max (%)	Manganese Mn max (%)	Phosphorus P max (%)	Sulphur S max (%)
B1	0.45	0.35	0.80	0.040	0.040
B2	0.55	0.35	0.90	0.040	0.040
B3	0.60	0.40	1.00	0.035	0.035
B4	0.65	0.40	1.10	0.035	0.035
B5	0.67	0.45	1.20	0.030	0.030
B6	0.70	0.45	1.30	0.030	0.030

(Source: UIC 810-1, 5th ed., 2003, Appendix A)

For ladle analysis, the purchaser may permit deviations from the above values according to Appendix C of the specification. Typical permissible reductions for ladle analysis are 0.02% for carbon and 0.05% for manganese from the product analysis maxima (Source: UIC 810-1, Appendix C).

What Are the Dimensional Tolerances for Rough Tyres?

Chapter 8 of UIC 810-2 specifies the dimensional and geometrical tolerances that a rough-rolled tyre must satisfy before acceptance. These tolerances are critical because the rough tyre serves as the blank from which the final tyre profile will be machined; excessive deviation at the rough stage may leave insufficient material for final finishing or may introduce residual stress imbalances.

Dimensional Tolerances for Rough-Rolled Tyres

Parameter	Tolerance Limit	Measurement Method
Outside diameter deviation from nominal	±3 mm for diameters ≤ 1,000 mm; ±4 mm for diameters > 1,000 mm	Diametral tape or calibrated calliper
Bore diameter deviation from nominal	+1.5 mm / -0 mm (positive only)	Internal micrometer at three circumferential positions
Concentricity (outside diameter relative to bore)	≤ 1.5 mm TIR	Rotate tyre on mandrel, dial indicator on OD
Axial runout (face wobble)	≤ 2.0 mm TIR measured at tyre rim	Tyre mounted on horizontal axis, indicator on side face
Radial thickness variation	≤ 2.5 mm	Ultrasonic thickness gauge at 12 equally spaced points
Out-of-roundness (ovality)	≤ 2.0 mm	Difference between maximum and minimum OD at 45° intervals
Flatness of tyre rim faces	≤ 1.0 mm over 100 mm length	Straight edge and feeler gauge

(Source: UIC 810-2, 4th ed., 1985, clause 4.4)

The tolerances apply to tyres in the rough-rolled condition, i.e., before any machining operations have been performed. Forging and rolling scale must be removed from surfaces that will be machined, but may remain on non-machined areas provided it does not exceed 0.5 mm in thickness (Source: UIC 810-1, clause 3.3).

Machining Allowances

The purchasing railway must specify the required machining allowances in the order. If not specified, the following default allowances apply:

Surface	Minimum Machining Allowance (per side)
Tread outer surface	4 mm
Tyre bore	3 mm
Tyre side faces (each)	2 mm
Flange outer face	5 mm

(Source: UIC 810-2, clause 4.4.2)

What Non-Destructive Testing Does UIC 810-2 Mandate?

Every tyre produced under UIC 810-2 must undergo ultrasonic testing (UT) to verify internal soundness. The standard specifies two permitted UT procedures: the comparative tyre method and the DGS (AVG) method.

Ultrasonic Test Acceptance Criteria

Defect Class	Equivalent Reflector Diameter	Application
Class A	2 mm disc-shaped reflector (DSR)	Tyres for high-speed passenger stock (v_max > 160 km/h) and locomotives
Class B	3 mm disc-shaped reflector (DSR)	Tyres for freight wagons and slower passenger stock (v_max ≤ 160 km/h)

(Source: UIC 810-1, 4th ed., 2000, clause 4.2.2.4)

In addition to the reflector-based criteria, the ultrasonic test must demonstrate that:

There is no attenuation of the back-wall echo greater than or equal to 15 dB/m at any scanning position.
No echo pulses attributable to internal flaws exceed the reference reflector amplitude at the same distance.
The entire tyre volume is scanned, including the rim, web, and hub regions.

Where magnetic particle testing (MT) is stipulated in the order, the following rejection criteria apply:

Surface Condition	Maximum Permissible Linear Indication Length
Machined surfaces	2 mm
Unmachined surfaces	6 mm

(Source: UIC 810-1, clause 4.2.2.5)

Every tyre must be traceable to its cast number, heat treatment batch, and inspection records. Test results must be retained for a minimum of five years after delivery (Source: UIC 810-1, clause 4.2.2).

Comparison Table: UIC 810-2 vs. EN 13262:2020

Parameter	UIC 810-2 + 810-1 (1985/2003)	EN 13262:2020
Scope	Rough-rolled non-alloy steel tyres only (tractive and trailing stock)	Monobloc wheels and tyred wheels (complete wheelset components)
Steel grades	B1 through B6 (six grades) with defined C, Si, Mn, P, S limits	ER1 through ER9 (nine grades) with additional alloying elements (Cr, Ni, Mo, V)
Ultimate tensile strength range	540 MPa (B1) to 980 MPa (B6)	620 MPa (ER1) to 1,200 MPa (ER9)
Ultrasonic test method	Comparative tyre or DGS (AVG); 2 mm or 3 mm DSR thresholds	Immersion technique with 100% rim and hub coverage; 1 mm DSR for high-speed wheels
Minimum detectable flaw size (high-speed)	2 mm DSR (Class A)	1 mm DSR
Attenuation limit	15 dB/m	Not specified (system performance verified by calibration blocks)
Magnetic particle test	Optional (required only if stipulated in order)	Mandatory for all finished machined wheels
Hardness homogeneity requirement	Maximum 30 HB variation within batch	Maximum 40 HB variation within cast or 15% of mean value
Legal status	UIC leaflet (industry standard, voluntary)	CEN European Standard (harmonised under EU Directives)
Current edition	4th (1985, still active) with 2003 amendments	2020 edition (supersedes EN 13262:2004+A2:2011)

(Source: UIC 810-1, 5th ed., 2003; EN 13262:2020; Rockstroh et al., 2006)

✍️ Editor’s Analysis

Where is UIC 810-2 being challenged by new technology?

The most significant challenge to UIC 810-2 is the shift from tyre-mounted wheels to monobloc wheels in high-speed and heavy-haul applications. EN 13262 defines nine steel grades (ER1–ER9) with tensile strengths up to 1,200 MPa, compared with B6’s 980 MPa limit. High-speed trains such as the ICE 4 and TGV M use monobloc wheels exclusively, rendering the tyred wheel obsolete for new-build high-speed fleets. However, tyre replacement remains economically essential for legacy fleets: replacing a worn tyre on a Re 4/4 II locomotive costs approximately €8,500 per wheelset, whereas replacing a monobloc wheel of equivalent size costs €18,000 to €22,000. For operators with large fleets of tyred-wheel stock (Deutsche Bahn alone operates approximately 1,800 class 101, 120, and 151 locomotives with tyred wheels), the economics strongly favour continued use of UIC 810-2 specifications.

A specific industry debate: the ultrasonic testing transition

The 2003 revision of UIC 810-1 allowed either comparative tyre or DGS (AVG) methods for ultrasonic testing. However, EN 13262 mandates immersion technique with 100% rim and hub coverage and a 1 mm DSR detection threshold for high-speed applications—significantly more sensitive than UIC’s Class A (2 mm). This creates a compliance gap for tyred wheels that operate on TEN infrastructure but are not covered by EN 13262’s scope. Some infrastructure managers, including SNCF Réseau and Network Rail, have begun requiring tyre manufacturers to demonstrate 1.5 mm DSR capability as a contractual condition, even when the formal standard permits 2 mm. The UIC working group on running gear has been discussing a revision to 810-2 since 2019, but no publication date has been announced.

The standard’s limitations and workarounds

UIC 810-2 specifies dimensional tolerances for rough tyres only. It does not address the interference fit calculation for shrink fitting, which is instead covered by individual railway specifications (e.g., Trenitalia IP 3156:2013, Deutsche Bahn Ril 931.0010). The standard also lacks guidance on residual stress measurement—a notable omission given that residual compressive stress in the tyre tread is critical for fatigue life. Modern monobloc wheel standards (EN 13262, AAR M-107) require residual stress verification by X-ray diffraction or sectioning methods. No such requirement exists for UIC 810-2 tyres, relying instead on heat treatment parameters as a proxy for residual stress control.

The 15 dB/m attenuation limit, while effective for detecting gross defects, is less sensitive than modern phased-array UT systems, which can detect 0.5 mm DSR reflectors. Tyre manufacturers such as Lucchini RS and Bochumer Verein Verkehrstechnik (BVV) have voluntarily adopted phased-array UT for all production, but this exceeds the standard’s requirements and is not enforced uniformly across suppliers.

— Railway News Editorial

❓ What is the difference between UIC 810-1 and UIC 810-2?

UIC 810-1 (5th edition, January 2003) is the primary technical specification for rough-rolled non-alloy steel tyres. It covers the full scope of procurement requirements including: chemical composition limits for six steel grades (B1–B6), heat treatment procedures (normalising for B1–B4, quenching and tempering for B5–B6), mechanical properties (tensile strength, yield strength, elongation, impact toughness for classes B3–B6), ultrasonic testing procedures and acceptance criteria (2 mm or 3 mm DSR thresholds, 15 dB/m attenuation limit), magnetic particle test criteria, and manufacturing process requirements (electric furnace or basic oxygen steelmaking with vacuum degassing). UIC 810-2 (4th edition, January 1985) is a complementary 8-page specification that exclusively addresses dimensional and geometrical tolerances for rough tyres. It specifies permissible deviations for outside diameter (±3 mm for diameters ≤1,000 mm), concentricity (≤1.5 mm TIR), axial runout (≤2.0 mm), radial thickness variation (≤2.5 mm), out-of-roundness (≤2.0 mm), and flatness (≤1.0 mm per 100 mm). The two leaflets are intended to be used together: the purchaser specifies the steel class and heat treatment from 810-1, and the dimensional tolerances from 810-2. (Source: UIC 810-1, 5th ed., 2003; UIC 810-2, 4th ed., 1985)

❓ Which steel grade should I select for a locomotive tyre operating at 140 km/h with disc brakes?

For a locomotive tyre operating at 140 km/h with disc brakes, the recommended steel grade is B4 or B5. B4 (normalised condition) provides ultimate tensile strength of 780 MPa and impact toughness of 25 J (U-notch). The normalised microstructure (fine ferrite-pearlite) offers good thermal fatigue resistance, which is important for disc-braked locomotives where heat input into the tyre during repeated braking cycles is higher than tread-braked vehicles. B5 (hardened and tempered) provides 880 MPa tensile strength and the same 25 J impact toughness, but the quenched and tempered structure (tempered martensite or bainite) offers better wear resistance at the cost of slightly lower ductility (10% elongation vs. 12% for B4). For 140 km/h operation, either grade is acceptable. However, if the locomotive also operates on lines with curvature radius below 300 metres (causing higher lateral forces), B5’s higher yield strength (540 MPa vs. 490 MPa for B4) provides additional margin against plastic deformation of the tyre bore during shrink fitting. For fleets that share tyres between locomotives and trailing stock, B3 (690 MPa) is often specified as a compromise grade acceptable to both applications. (Source: UIC 810-1, Appendix A; EN 13262:2020 annex; CIFI, 2019)

❓ Can I machine a rough tyre that exceeds the UIC 810-2 out-of-roundness tolerance?

Exceeding the UIC 810-2 out-of-roundness tolerance (≥2.0 mm ovality) does not automatically render the tyre unusable, but it requires careful engineering assessment. The primary risk is unbalanced material removal during final machining. If a tyre with 2.5 mm ovality is machined to a finished outside diameter, the depth of cut will vary around the circumference by at least the ovality value. This results in uneven removal of the decarburised layer and may expose regions with different residual stress states. In extreme cases (ovality exceeding 4 mm), the tyre may require an additional rough-machining pass before finishing, which reduces the available machining allowance and may result in a finished tyre with tread thickness below the minimum specified value (typically 50 mm for standard-profile tyres). The purchasing railway’s engineering department must approve any tyre with ovality between 2.0 mm and 3.0 mm on a case-by-case basis. For ovality exceeding 3.0 mm, the tyre shall be rejected without exception. Operators should note that out-of-roundness is measured on the tyre as a free ring—not after shrink fitting. A tyre that is oval as a free ring will typically become round after shrink fitting onto a round wheel centre due to the elastic deformation of the interference fit, but the residual stress distribution will be asymmetric. (Source: UIC 810-2, clause 4.4; CIFI, 2019, slide 15)

❓ How does the ultrasonic testing requirement in UIC 810-2 compare with modern European wheel standards?

The ultrasonic testing (UT) requirements in UIC 810-2 are significantly less stringent than those in EN 13262:2020 for monobloc wheels. UIC 810-2 permits two UT methods: comparative tyre (using a reference tyre with artificial defects) or DGS (AVG) method. The minimum detectable flaw size for Class A defects (high-speed stock) is 2 mm equivalent disc-shaped reflector (DSR). For Class B defects (freight and slower stock), the limit is 3 mm DSR. The standard also requires that back-wall echo attenuation not exceed 15 dB/m. EN 13262:2020, by contrast, mandates immersion technique UT with 100% coverage of the wheel rim and hub, and for high-speed wheels (v_max > 160 km/h) the minimum detectable flaw size is 1 mm DSR. The EN standard does not specify an absolute attenuation limit; instead, it requires system performance verification using calibration blocks containing reference reflectors at depths ranging from 10 mm to the full rim thickness. For locomotive wheels, EN 13262 requires 2 mm DSR detection. The practical implication is that a tyre passing UIC 810-2 UT may contain a 1.5 mm internal inclusion (half the thickness of a human hair) that would be detected and rejected under EN 13262. This gap is significant for tyres that operate on high-speed lines (160–200 km/h) even if the vehicle’s maximum speed is lower. (Source: UIC 810-1, clause 4.2.2.4; EN 13262:2020, clause 5.4; Rockstroh et al., 2006, Fraunhofer IZFP)

❓ Are tyres manufactured to UIC 810-2 allowed to operate on EU TEN network lines?

Yes, tyres manufactured to UIC 810-2 may operate on the EU Trans-European Network (TEN) provided the vehicle as a whole is authorised for TEN operation under the Technical Specifications for Interoperability (TSI). However, the situation is nuanced. The TSI Locomotive and Passenger Rolling Stock (LOC&PAS), Regulation (EU) 1302/2014, requires that wheelsets conform to EN 13262 for monobloc wheels or EN 13260 for wheelsets. It does not explicitly reference UIC 810-2. Therefore, a vehicle with tyred wheels cannot claim TSI conformity solely on the basis of UIC 810-2 compliance. In practice, vehicles with tyred wheels that were authorised before the LOC&PAS TSI came into force (1 January 2016) operate under “grandfather rights” provided they remain within their original authorisation scope. For new vehicles, or for substantial modifications of existing vehicles, the wheelset must comply with EN 13262 or an equivalent standard accepted by the European Union Agency for Railways (ERA). Some ERA-recognised Notified Bodies accept UIC 810-2 as equivalent to EN 13262 for tyred wheels of locomotives with maximum speed ≤ 160 km/h, but this is decided on a case-by-case basis. Operators planning cross-border service on TEN lines should consult their NoBo before procuring tyres under UIC 810-2. (Source: ERA, TSI LOC&PAS 1302/2014, annexes 2 and 5; OTIF RID, 2023)

Railway News Technical Team

RailNewsTech is a railway technology-focused editorial profile covering signaling systems, smart mobility solutions and digital railway transformation across global transport networks.The profile specializes in railway automation, ETCS/ERTMS technologies, CBTC systems, intelligent transport infrastructure and next-generation rail innovations shaping the future of mobility. Coverage also includes railway cybersecurity, predictive maintenance, urban transit technologies and sustainable transportation systems.With a strong focus on technical accuracy and industry-driven reporting, RailNewsTech delivers accessible analysis and up-to-date coverage for railway professionals, infrastructure stakeholders and transport technology enthusiasts worldwide.