>>Please download the YOKOHAMA Tyre Pressure Handbook 2010/11 here

Please use this handbook as a basic guideline. There might be the possibility that the handbook doesn't meet  the regulation in your country. You can find your precise tyre pressure either in fuel door or in the handbook of your car. You can always contact your local YOKOHAMA or car dealer for personal advise.

Match Mounting

Mounting Procedures

For the proper mounting of YOKOHAMA tyres, be sure to observe some basic precautions:

• Wheel is securely seated on the hub face.
• All lugs have proper torque.
• There is no buildup of dirt between the hub and wheel.
• The wheel is not bent.
• Both tyre beads are securely seated on the rim.

Custom or Alloy Wheels

While custom or alloy wheels require an increased level of care over steel wheels, it is vitally important that each customer receives the highest level of service. There are several key points to note when mounting YOKOHAMA tyres. Following these basic precautions not only yields consistent results, but satisfied customers - and that translates into return business and new referrals.

Avoid scratching or bending alloy wheels during installation
These wheels are manufactured with extremely soft metals with a greater sensitivity to scratching and distortion under pressure. Modern tyre machines apply equal pressure to both top and bottom beads with no pressure on the wheel itself. A pad on the base of the mounting machine protects chrome-plated, painted or machined wheels from scratches and damage.

During the mounting process, proper lubrication is a must
Lubricate both top and bottom beads with an approved tire lubricant. If the beads do not seat at 40 psi, break the entire assembly down and re-lubricate the bead areas.


Observe match-mounting procedures

Proper tyre and wheel assembly balancing is important from a vehicle safety standpoint. In high-speed driving, improperly balanced tyre/wheel assemblies will cause a vehicle to lose stability and not operate in a safe and comfortable manner. Improperly balanced tyre/wheel assemblies also cause abnormal treadwear patterns.

To facilitate proper balancing, YOKOHAMA places red and yellow marks on the sidewalls of its tires to enable the best possible match-mounting of the tyre/wheel assembly. There are two methods of match-mounting YOKOHAMA tyres to wheel assemblies using these red or yellow marks:

• Uniformity (red mark)
• Weight (yellow mark)

Warning: Improper mounting, underinflation, overloading or tyre damage may result in tyre failure, which may lead to serious injury. Tyre and rim sizes must correspond for proper fit and application. Never exceed 40 psi to seat beads.

Warning: Tyre changing can be dangerous, and should be done only by trained persons using proper tools and procedures established by the Rubber Manufacturers Association. Failure to comply with proper procedures may result in incorrect positioning of the tyre, tube or wheel assembly, causing the assembly to burst with explosive force sufficient to cause serious physical injury or death. Never mount or use damaged tyres, tubes or wheel assemblies.



Uniformity Method

When performing uniformity match-mounting, the red mark on the tyre, indicating the point of maximum radial force variation, should be aligned with the wheel assembly's point of minimum radial run-out, which is generally indicated by a colored dot or a notch somewhere on the wheel assembly (consult manufacturer for details). Radial force variation is the fluctuation in the force that appears in the rotating axis of a tyre when a specific load is applied and the tyre rotated at a specific speed. It is necessary to minimize radial force variation to ensure trouble-free installation and operation. Not all wheel assemblies indicate the point of minimum radial run-out, rendering uniformity match-mounting sometimes impossible. If the point of minimum radial run-out is not indicated on a wheel assembly, the weight method of match-mounting should be used instead.



Weight Method

When performing weight match-mounting, the yellow mark on the tyre, indicating the point of lightest weight, should be aligned with the valve stem on the wheel assembly, which represents the heaviest weight point of the wheel assembly. After match-mounting by either of the above methods, the tyre/wheel assembly can be balanced.



Balancing

The technical definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. A balanced tyre is one where mass of the tyre - when mounted on its wheel and the car's axle - is uniformly distributed around the axle (its center of rotation). Balanced tyres can spell the difference between a positive and negative driving experience. Drivers of high performance vehicles will be more sensitive to imbalance problems, but no driver is happy with an annoying vibration.


An out-of-balance tyre and wheel assembly:

• Degrades ride quality and driver comfort.
• Shortens the life of tyres, bearings, shock absorbers and other suspension components. Vibration is the most noticeable effect of imbalance.
• It is dependent on vehicle speed.
• It often first becomes apparent between 50 and 60 km/h and increases in magnitude with greater speeds.
  
  

Sources of Imbalance

Two sources of imbalance occur in tyres: heavy or light spots in the tyre and radial or lateral run-out. Imbalance also can be caused by:

• Variations within the wheel, such as thickness and welds.
• Rotor and axle imbalances.
  
  

Heavy or Light Spot Imbalance

There are two types of imbalance caused by heavy or light spots: static and dynamic.

• Static imbalance: Occurs when there is a heavy or light spot in the tyre so that the tyre won't roll evenly and the tyre/wheel assembly undergoes an up-and-down movement.
• Dynamic imbalance: Occurs when there is unequal weight on both sides of the tyre/wheel assembly's circumferential centerline. The tyre/wheel assembly has a side-to-side movement.
  
  

Heavy or Light Spot Balancing

Achieved either statically or dynamically, depending on the type of imbalance that has occurred.

• Static balance: Achieved with a bubble balancer but does not correct for dynamic imbalance.
• Dynamic balance: Achieved with a spin balancer where the tyre/wheel assembly is balanced both statically and dynamically.

Radial or Lateral Run-out Imbalance

This results from poor bead seating on the rim or the placement of components. Poor bead seating is usually the result of improper mounting or the use of improperly made wheels. A small degree of this imbalance is acceptable, but too great a run-out causes vibration and excessive tyre wear.

• Radial Run-out: An "out-of-round" situation where vibrations are produced as the wheel spindle moves up and down.
• Lateral Run-out: A side-to-side or wobbling movement of the tyre and wheel. It is less common than radial run-out. Sensitivity of a vehicle to vibration from radial run-out is four to eight times that of wobble from lateral run-out.

Run-out Balancing

Depends on whether it is radial or lateral run-out.

• Radial run-out balancing: Achieved by rotating the wheel and tyre assembly two stud positions on the hub, or by rotating the tire 180° on the wheel. If run-out is still over specification, check wheel run-out and mark the low point. Rotate to match the high point of the assembly run-out with the wheel low point. If the assembly run-out is still too high and the wheel is within specification, replace the tyre.
• Lateral run-out: Achieved by using a run-out gauge to check both the tyre and wheel. Chalk-mark the highest point of run-out on both the wheel and tyre. Replace whichever (wheel, tyre, or both) is out of specification.

Alignment

For improved overall performance and extended tyre tread life under various driving conditions and speeds, it is imperative that the tyres be in proper alignment with the vehicle. Poor or improper alignment occurs when the suspension and steering systems are out of adjustment.

Several factors may be involved with poor alignment. Be aware that customers tend to replace tyres rather than correct the real problem-alignment. The result can be a dissatisfied customer who switches from one tyre manufacturer to the next with the same result and eventually goes elsewhere to buy new tyres.

For most vehicles, poor alignment results in excessive and/or uneven tyre wear. Improper alignment can reduce a tyre's life by more than 70%.



Improper Alignment and Correction

Poor or improper alignment typically results in a variety of abnormal treadwear patterns that are "readable." These clues often point to one or more sources of the problem that can be measured and corrected. But before taking any alignment measurements, check the following:

• Proper inflation of each tyre: Pressure over or under recommended levels will affect some alignment measurements.
• Ride height: Ride height is the distance between the vehicle's frame and the road. Because all alignment specifications are relationships between various suspension components, ride height becomes the reference point for all alignment measurements. Therefore, proper alignment is not possible if ride height is higher or lower than factory ride height specifications.