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sudharma · 02-28-2010, 06:34 AM

Quote:

Originally Posted by fireblah

I have seen in many tyres including bridgestone, a little yellow circle on the side.
Old fox told me this is a weight bias indicator, and I have seen the mark put right where the air valve of the wheel is.
Now, there was no such indicator on michelin.... anyone knows why? Or maybe Michelin does not need anything like that ?
Changed at 8500 Kms, price : 18k for the set (front and rear)

Please see below 2 writeups regarding weight bias marking on tires. One from Wikipedia & the other from YOKOHAMA TIRES

1) Additional marks

There are numerous other markings on a typical tire, these may include:

M+S, or M&S: Mud and Snow; all-weather tires, with above-average traction in muddy or very light snowy conditions, and for low ambient temperatures. Not a winter tire unless it has the snowflake and mountain symbol. Spike tires have an additional letter, "E" (M+SE).
BSW: Black SideWall
WSW: White SideWall
OWL: Outline White Lettering
E4: Tire approved according ECE-regulations, the number indicating the country of approval.
030908: Approval number of the tire
DOT code: All tires for use in the USA have the DOT code, as required by the Department of Transportation (DOT). It specifies the company, factory, mold, batch, and date of production (2 digits for week of the year plus 2 digits for year; or 2 digits for week of the year plus 1 digit for year for tires made prior to 2000). Although not law, some tire manufacturers do not suggest using a "new" tire that has been sitting on the shelf for more than 6 years (Ford Motor Company) or 10 years (Cooper Tire citing a tire association recommendation).[citation needed]
TL: Tubeless
TT: Tube-type, tire must be used with an inner-tube
Made in ...: Country of production
C: Commercial; tires for light trucks (Example: 185 R14 C)
B: Bias belted; tires for motorcycles (Example: 150/70 B 17 69 H)—diagonal construction with belt added under the tread
SFI, or Inner: Side Facing Inwards; inside of asymmetric tires
SFO, or Outer: Side Facing Outwards; outside of asymmetric tires
TWI: Tread Wear Indicator; a device, such as a triangle or a small Michelin Man icon, located where the tread meets the sidewall. It indicates the location of the raised wear bars in between the tire tread channels.
SL: Standard Load; tire for normal usage and loads
XL: eXtra Load; tire for vehicles of heavier standard weights
RF: Reinforced tires
Arrows: Some tread designs are "directional", and designed to perform better when driven in a specific direction (clockwise or counter-clockwise). Such tires will have an arrow showing which way the tire should rotate when the vehicle is moving forwards. It is important not to put a "clockwise" tire on the left hand side of the car or a "counter-clockwise" tire on the right side.
M0: Original tires for Mercedes-Benz
N*: Original tires for Porsche
"Star": Original tires for BMW

To facilitate proper balancing, most high performance tire manufacturers place laso red (uniformity) and yellow (weight) dots - marks on the sidewalls of its tires to enable the best possible match-mounting of the tire/wheel assembly.[11]

2) TIRE CARE - by YOKOHAMA

MATCH MOUNTING

Mounting Procedures
For the proper mounting of Yokohama tires, be sure to observe some basic precautions:
1. Wheel is securely seated on the hub face.
2. All lugs have proper torque.
3. There is no buildup of dirt between the hub and wheel.
4. The wheel is not bent.
5. Both tire 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 tires. 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 tire 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 tire and wheel assembly balancing is important from a vehicle safety standpoint. In high-speed driving, improperly balanced tire/wheel assemblies will cause a vehicle to lose stability and not operate in a safe and comfortable manner. Improperly balanced tire/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 tire/wheel assembly. There are two methods of match-mounting Yokohama tires to wheel assemblies using these red or yellow marks:

Uniformity (red mark)
Weight (yellow mark)

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

Warning: Tire 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 tire, 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 tires, tubes or wheel assemblies.

Uniformity Method
When performing uniformity match-mounting, the red mark on the tire, 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 tire when a specific load is applied and the tire 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 tire, 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 tire/wheel assembly can be balanced.