Prohibition of operation of M2 and M3 buses at critical tire tread depth: standards

Operation of bus categories M2 (weighing 3.5–5 tons) and M3 (over 5 tons) is prohibited if the remaining tire tread depth is less than 2 mm - this requirement is enshrined in Appendix 1 to the Traffic Regulations of the Russian Federation (clause 5.1) and Technical Regulations of the Customs Union 018/2011. Violation of the norm entails not only a fine of up to 500 rubles for the driver, but also suspension of the diagnostic card during inspection. Critical tread wear on buses increases the risk of aquaplaning by 3 times, and braking distance on a wet road by 40–60%. In this article we will look at how to correctly measure the residual depth, which tires must be replaced, and what to do if a traffic police inspector identifies a violation.

Particular attention is paid to buses operated in commercial transportation (minibus taxis, intercity flights, school buses). They are subject to enhanced checks: according to Order of the Ministry of Transport No. 286, the remaining tread depth must be checked at least once every 10,000 km. Moreover, for winter tires (with marking M+S, 3PMSF) the minimum threshold remains the same - 2 mm, but actual wear to this value occurs faster due to the soft rubber.

1. Regulatory requirements for the tread depth of M2/M3 buses in 2026

According to the current edition Traffic rules of the Russian Federation (clause 5.1) and Technical Regulations CU 018/2011, for bus categories M2 and M3 The following requirements are established:

• 📏 Minimum remaining tread depth: 2 mm for all positions (front/rear axle, drive/drive wheels).
• ❄️ Winter tires: allowed for use only with marking M+S, 3PMSF or M&S in the period from December to February (in some regions - from November to March).
• 🔄 Variation of width: It is prohibited to install tires with different remaining tread depths on the same axle (the permissible difference is no more than 5 mm).
• 🚫 Damage: Tires with cracks, cord delaminations, exposed threads or local swelling are prohibited.

Important: the requirements for buses are stricter than for cars (where the minimum depth is 1.6 mm). This is due to increased responsibility for the safety of passengers and the greater mass of the vehicle. For example, a bus Mercedes-Benz Sprinter (category M2) weighs up to 5 tons when fully loaded, and the braking distance on worn tires increases by 20–30 meters at a speed of 80 km/h.

2. Consequences of operating a bus with worn tires

Ignoring tread depth standards entails not only administrative liability, but also technical risks:

Consequence	Description	Probability with residual depth <2 mm
Hydroplaning	Loss of traction on wet surfaces due to inability to drain water	High (risk +300%)
Extending the braking distance	On dry asphalt +15%, on wet asphalt - up to +60%	Average
Tire rupture	Due to thinning cord and overheating under high loads	Low (but critical)
Traffic police fine	500 rubles (Part 1 of Article 12.5 of the Code of Administrative Offenses of the Russian Federation) or a ban on operation	100%

Case study: in 2023 Rostov region bus PAZ-3205 (category M3) with a remaining tread depth of 1.5 mm got into an accident on a wet road - the braking distance was 85 meters instead of the standard 50. As a result, 12 passengers were injured. The examination found that the reason was the inability to drain water from under the wheels.

⚠️ Attention: If the traffic police inspector reveals tread wear below normal, he has the right prohibit further movement bus until the violation is eliminated (clause 2 of article 27.13 of the Code of Administrative Offenses of the Russian Federation). In this case, you will have to call a tow truck or replace the tires on the spot.

3. How to correctly measure the remaining tread depth

Checking the tread depth should be carried out at least 6 points on each wheel: in the center and along the edges of the treadmill. The following methods are used:

1. Caliper or depth gauge:
   • 📐Measurement accuracy: ±0.1 mm.
   • 🔍 It is necessary to clean the protector from dirt and stones.
   • 📌 Measurements are carried out in three longitudinal grooves (central and two lateral).
2. Wear indicators:
   • 🟡 There are marks on the tire (usually 2-4 mm). If the tread has worn down to the level of the mark, the tire needs to be replaced.
   • 🔎 U Michelin and Continental indicators are made in the form of a brand logo.
3. Coin test (express check):
   • 💰 Insert the 10-kopeck coin edgewise into the protector. If the rim is visible, the depth is <2 mm.
   • 🚨 The method is approximate, not suitable for official checks.

1. Clean the tread from dirt and stones

2. Check the depth at 6 points on each wheel

3. Make sure there is no local damage (cracks, blisters)

4. Compare the indicators on the same axis (the difference is no more than 5 mm)

5. Check the tire pressure (for M3: 7–9 atm)

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For buses Volvo 9700 (category M3) the manufacturer recommends using laser depth gauges, since their tires have a complex tread pattern with many grooves. The error of mechanical devices in this case can reach 0.3 mm.

4. Which tires are subject to mandatory replacement?

Tire replacement is required not only when the tread depth is critical, but also in the following cases:

• 🔥 Local damage: cracks more than 25 mm long, cord delamination, exposed threads.
• 🌀 Uneven wear: If the difference in tread depth on one wheel exceeds 2 mm.
• 📅 Service life: Tires older than 5 years (even with a residual depth of 3–4 mm) must be replaced due to aging of the rubber.
• 🚗 Inappropriate for the season: summer tires in winter or winter tires in summer (fine 500 rubles).

Particular attention is paid driving wheels bus. For example, on Scania Touring (category M3) the rear axle is the driving one, and its tires wear out 20% faster than the front ones. Manufacturer recommends rotation of wheels every 20,000 km for even wear.

List of tires prohibited for use on M2/M3 buses

- Retreaded tires (prohibited for M3 from 2021).

- Tires with a lower speed index L (120 km/h).

- Tires with a load index lower than that specified in the PTS.

- Tires with visible signs of repair of side cuts (prohibited for M3).

⚠️ Attention: If the bus is equipped with tires with different tread patterns on one axis, this is equivalent to operation with malfunctions (fine 500 rubles). An exception is the temporary replacement of one wheel in an emergency (no more than 1 day).

5. Fines and liability for violation of standards

The following sanctions are imposed for operating a bus with worn tires:

Violation	Fine (Administrative Code of the Russian Federation)	Additional measures
Residual depth <2 mm	500 rubles (Part 1, Article 12.5)	Prohibition of operation until elimination
Different tires on one axle	500 rubles (Part 1, Article 12.5)	—
Lack of winter tires during the season	500 rubles (Part 1, Article 12.5)	Evacuation to impound lot (in some regions)
Tires with damage (cracks, bulges)	500–1000 rubles (Part 1, Article 12.5)	Prohibition of operation

For legal entities (vehicle fleets, transport companies) fines are higher: up to 50,000 rubles for systematic violation (Article 12.31.1 of the Code of Administrative Offenses of the Russian Federation). In addition, in case of an accident with victims due to worn tires, the blame falls entirely on the carrier, which entails civil liability (compensation for damage) and possible criminal prosecution according to Art. 264 of the Criminal Code of the Russian Federation.

6. How to avoid problems: prevention and recommendations

To prevent operating a bus with worn tires, follow these rules:

• 📅 Scheduled inspection: Measure the tread depth every 5,000 km (for M3) or 10,000 km (for M2).
• 🔄 Wheel rotation: Rotate front and rear tires every 20,000 km to ensure even wear.
• ⚖️ Pressure control: Maintain pressure within the limits specified by the manufacturer (for example, for MAN Lion’s Coach - 8.5 atm).
• 🛠️ Seasonal replacement: Install winter tires in advance (in October–November), as they take 200–300 km to break in.
• 📑 Logging: Record the dates of inspections, replacements and rotations for presentation to the inspector.

For buses operating in mountain regions (for example, KamAZ-6282 on routes of the North Caucasus), it is recommended to use tires with reinforced tread (new tread depth 10–12 mm). This increases the service life by 15–20% and improves grip on serpentine roads.

7. Frequently asked questions about the operation of tires on M2/M3 buses

❓ Is it possible to ride an M3 bus with a residual tread depth of 1.9 mm?

No, this is a violation. Minimum permissible depth - 2 mm. At 1.9 mm, the traffic police inspector has the right to prohibit operation and issue a fine of 500 rubles.

❓ Which tires are better to choose for the M3 intercity bus?

For intercity transportation, tires with low rolling resistance (for example, Continental EcoPlus or Michelin X Multi Energy) and a tread depth of at least 8 mm in new condition. They provide fuel efficiency and a long service life.

❓ What to do if there are tires with different tread depths on the same bus axle?

Necessary level out wear by rotating the wheels or replacing a more worn tire. The difference in depth on one axis should not exceed 5 mm (according to GOST 33997-2016).

❓ Is it possible to restore the tread on M3 bus tires?

No, for category buses M3 retreading is prohibited from 2021 (clause 5.5 Technical Regulations CU 018/2011). For M2, restoration is allowed, but only in certified workshops.

❓ What documents does the inspector check when stopping the bus?

The inspector has the right to request:

• 📄 Diagnostic card (with a mark about checking the tires).
• 📋 Waybill (for commercial transportation).
• 🚗 Vehicle registration certificate.

In the absence of a diagnostic card, the fine will be 2,000 rubles (Part 2 of Article 12.1 of the Code of Administrative Offenses of the Russian Federation).