Checking the condition of tires and their pressure, designating tires and wheel rims, rotating wheels (Mercedes-Benz M-Class W163)

1. Depending on the model and equipment, tires and wheels of different sizes may be installed. The wheels have a pressing depth of 38 mm - the pressing depth is the distance from the center of the wheel to the thrust surface of the brake disc or drum. Wheel bolts for steel and alloy wheels are the same size.

Note: When installing alloy wheels from other manufacturers, different bolt sizes may be required.

Technology is improving. It may be that older models may have different tire pressure values. The dimensions specified in the vehicle documents are decisive.

2. For sporty driving, it is recommended to increase the pressure in the front and rear tires by 0.2 kgf/cm². When increasing the pressure, you should proceed from the base value for different load conditions.

3. Winter tires usually have a pressure 0.2 kgf/cm² higher than summer tires. The recommendations of winter tire manufacturers should be taken into account.

4. Since winter tires have a speed limit, a sign indicating the maximum speed must be affixed within the driver's field of vision.

Disc designations

Example 6Jx15

• 6 - Wheel width in inches
• J — Letter designation of the height and contour of the side flange of the disk rim
• x — Designation of a solid deep disc
• 15 — Disc diameter in inches
• Permissible lateral runout on the side edge of the disc: 0.8 mm;
• Permissible radial runout on the disk seat: 0.5 mm.

Tyre designation

Example: 195/70 R 14 89 H

• 195 — Tire width in mm
• /70 — Height to width ratio (the height of the tire cross-section is 70% of the width)

Note: If separate width to height ratio information is missing (for example, 175 R 14), then we are talking about a "normal" ratio. It is 82%.

• H — Speed class, H: up to 210 km/h (on new tires it is not always given).
• R — Radial design
• 14 - Disc size in inches
• 89 — Load capacity parameter

Note: If there is an M+S designation between data 14 and 89, these are winter tyres.

• H — Designation of the permissible maximum speed.

Note: Speed symbols apply to both summer and winter tyres. Speed letter designations are given in the Specifications.

Date of tire manufacture

The date of manufacture is indicated on the tire in the manufacturer's code.

Example: DOT CUL2 UM8 019 TUBELESS

• DOT — Department of Transportation (US Department of Transportation)
• CU — abbreviation of the manufacturer's name
• L2 — tire size
• UM8 — tire design
• 4600 - production date - 46th working week of 2000
• TUBELESS — tubeless (TUBETYPE - tire with tube)
• Regularly checking your tires will help you avoid the hassle of being stopped on the road due to a flat tire. In addition, such checks provide valuable information about possible problems with the steering and suspension before serious damage occurs.
• The tires are equipped with built-in tread wear indicator strips that are exposed when the tread depth decreases to 1.6 mm, after which the tires are considered worn. This value represents the minimum permissible tread depth; in most cases, it is recommended to replace tires with a tread depth of 2 mm or less. Tread depth can also be determined using a simple and inexpensive device known as a tread depth gauge.

• Pay attention to any unusual tread wear. Tread defects such as cavities, bulges, flat spots and more severe wear on one side indicate a violation of the front wheel alignment angles and/or wheel balancing. If any of these defects are detected, contact a tire repair shop for correction.
• Check the tire carefully for cuts, punctures, and stuck nails or tacks. Sometimes, after a tire has been punctured by a nail, it will hold its pressure for a while or deflate very slowly. If you suspect a "slow puncture," first check the valve nipple for leaks. Then inspect the tread for any foreign objects stuck in it or previously repaired punctures that have begun to leak air again. If you suspect a puncture, you can confirm its presence by wetting the suspected area with soapy water. If there is a leak, the solution will begin to bubble. If the puncture is not too large, the tire can usually be repaired at any tire shop.
• Carefully inspect the inside sidewalls of the tires for signs of brake fluid leakage. If any, have the brake system checked immediately.
• Maintaining the correct tire pressure increases their lifespan, helps save fuel, and improves overall driving comfort. A special pressure gauge is required to check the pressure.

Note: Always keep an accurate pressure gauge in your glove compartment - pressure gauges built into air hose nozzles at petrol stations should not be trusted.

• Always check tire pressure when tires are cold (i.e. before traveling by car). If you check the pressure on warm or heated tires, this will lead to overestimation of the pressure gauge readings due to thermal expansion of the tires. In this case, you should never lower the pressure, because after the tire cools down, it will be lower than normal.
• Unscrew the protective cap from the inflation valve protruding from the wheel rim or hub cap, then firmly press the pressure gauge nozzle onto the valve. Read the readings and compare them with those recommended in the Specifications. Remember to replace the protective cap to prevent dirt and moisture from entering the valve mechanism. Check the pressure in all four tires and inflate them to the recommended pressure if necessary.
• Don't forget to maintain the required pressure in the spare tire.

Checking the air pressure in the tires

Note: Checking air pressure should only be done on cold tires.

The tire pressure values given for a light vehicle load are the minimum values that ensure comfortable driving. Increased tire pressure, provided for a heavy vehicle load, has a positive effect on vehicle controllability even under light load and is entirely acceptable. However, rolling smoothness is somewhat reduced.

1. Unscrew the valve cap.

2. Tire pressure is checked once a month and also during maintenance (including spare tire). When checking, use a special pressure gauge or a pressure gauge built into the compressor.

Note: Do not rely on the pressure gauges built into the compressor nozzles used to inflate tires at petrol stations.

3. In addition, air pressure must be checked before each long trip, since in this case the temperature load on the tires increases.

4. The required air pressure in the tires is indicated on the sticker located on the inside of the fuel tank cap.

Note: When using winter tires, the air pressure should be increased by 0.2 kgf/cm² relative to the set value.

5. The air pressure of the narrow spare tires is indicated on the sidewall of the rim. The air pressure in the tires changes depending on the change in the ambient air temperature by 10°C by approximately 0.1 kgf/cm². This should be taken into account when checking the air pressure in the tires indoors, especially in the cold season.

Example:

• The temperature in the garage is about +20°C
• Outside air temperature - About 0°C
• Set tire pressure = Prescribed value + 0.2 kgf/cm²

Checking the condition of tire inflation valves

Note: The valve extensions used must be checked for damage and contamination that could cause leaks. If necessary, the extensions must be replaced.

1. Unscrew the protective cap and extension.

2. Apply a small amount of soap solution or saliva to the valve. If an air bubble forms, tighten the insert (3) - use the projection of the metal protective cap (2).



3. Check the valve again. If bubbles appear and the valve cannot be tightened, it should be replaced (work of the service station).

4. Be sure to reinstall the protective cap.

Examples of typical tire tread wear

Lateral wear

Underinflation causes the tire to overheat while driving due to excessive deflection, which means the tread is not pressed down sufficiently onto the road surface. This results in loss of traction and excessive tread wear, not to mention the risk of tire failure due to overheating.

Check and adjust pressure.

Incorrect wheel alignment (wear on one side)

Repair or replace suspension parts.

Too sharp turns

Slow down!

Central wear

Excessive pressure

Overinflation of a tire results in accelerated wear of the center tread, reduced traction, harsher ride, and an increased risk of fatal tire damage.

Check and adjust pressure.

If you have had to inflate your tyres to the pressure specified in the Specifications for heavy loads, be sure to deflate them when returning to normal operation.

Uneven wear

The tires of the front wheels may wear out unevenly as a result of incorrect adjustment of the wheel alignment angles. You can check and adjust the installation angles for a reasonable fee in most tire repair shops.

Incorrect camber or runout

Repair or replace suspension parts.

Suspension defect

Repair or replace suspension parts.

The wheels are out of balance

Balance the wheels.

Front wheel alignment is incorrectly set

Adjust the front wheel alignment angles.

Note: Frayed edges of the tread pattern, which is a sign of wear, are best detected by touch.

Wheel rotation

Note: Wheel rotation is only permitted when the front and rear wheel assemblies are the same size.

1. Rotate the wheels every 5-10 thousand kilometers depending on the degree of wear of the tires. Make sure to maintain the direction of rotation of the wheels (for directional tires).

2. Rotation must be performed before the characteristic signs of tire wear appear: wear of the shoulder area (front wheels)/middle part of the tread (rear wheels).

3. Clean the inside of the wheel assemblies thoroughly at each rotation.

4. After completing the procedure, do not forget to check the tire inflation pressure (see above).

Attention! To avoid loosening of the wheels, tighten the wheel bolts strictly in accordance with the requirements of the Specifications, use only genuine wheel bolts with the Mercedes-Benz logo!

Lightweight spare wheel

1. If a tyre is damaged, a spare wheel of a lightweight design is installed in place of the failed wheel assembly, which should be replaced with a standard design wheel at the first opportunity - the spare wheel is designed for a mileage of no more than 20,000 km.

2. If necessary, the spare wheel tire can be mounted on the working wheel, provided that it matches the size of the other working wheels.

Note: Tires that have been in use for more than 6 years are recommended to be used only in extreme cases when there is no other way out.

Models with AMG equipment

Warning! There is a risk of accident! If a lightweight spare wheel is mounted, the dynamic properties of the vehicle must be taken into account due to the different tire sizes. Adapt your driving style to this situation.

1. The lightweight spare wheel is intended for short-term use only, subject to the prescribed air pressure in the tires and a maximum speed of 80 km/h.

2. Operation with more than one lightweight spare wheel is not permitted.

Wheel replacement

See Section Jacking and towing.

Wheel mounting bolts

1. Wheel bolts damaged mechanically or as a result of corrosion must be replaced.

2. Before screwing in, wheel bolts should not be lubricated with any compounds.

3. If the thread in the wheel hub is damaged, the vehicle should be immediately taken to a Mercedes-Benz service station to have the necessary repairs carried out.

4. Before installing the wheels, check the cleanliness of the mating surfaces of the discs and hubs.

5. To avoid loosening of the wheels, tighten the wheel bolts strictly in accordance with the requirements of the Specifications, use only genuine wheel bolts with the Mercedes-Benz logo!