How does Shinko know that EVERY wheel with EVERY valve will be heavy?
Peter:
You indicated a red dot in your initial post. I didn't click on to the colour because there was only discussion of the one dot. I had the feeling that I was missing something and reading it again the red sparked my memory cells. So,
if the motorcycle tire industry uses the same protocols as the car tire industry does, and
if my recollection is correct, my response to you in post # 6 above is incorrect. The red dot is not for balance but rather run-out.
With regards to car tires;
Tire manufacturers don't know where the heaviest point of your, or anyone else's wheel is. Tire manufacturers have no control over where or how any given tire is going to be installed in the retail environment. All that they can do is indicate where the static lightest balance point of the tire is. Proper balancing instructions detail that the static lightest point of the tire is to be aligned with the static heaviest point of the wheel- not the valve. However, there is no way for a tire installer to know where the static heaviest point of any wheel is without checking the wheel without a tire installed. Customers aren't going to be willing to pay for this extra work to determine that point. It is also not considered necessary as this is only used as an initial balance. For the majority of wheels the heaviest point will be in the vicinity of the valve. Aligning the dot with the valve puts the lightest part of the tire in close enough proximity to the heaviest part of the wheel to achieve this initial balance. This is only intended to be an initial balance. Its purpose is to reduce the amount of weight needed to achieve the final balance. This is because excessive amounts of wheel weights can result in shimmies, vibrations, etc., due to a physics priciples that I no longer remember. For this reason proper balancing instructions, and all shop manuals, list a maximum amount of weight that should be used to balance a wheel and tire assembly. The final balance is determined and achieved using an accurate dynamic balancer. The accuracy of the final balance achieved using a dynamic balancer renders the initial balance irrelevant other than that it served to reduce the amount of weight required to achieve the final balance.
As for the colour and number of dots on tire sidewalls- I am reaching way back in my memory cells so this may not be gospel but this is the way that I remember it;
Tires that were supplied by the tire manufacturers directly to the car manufacturers had two dots- one red and one other colour.
The red dot indicated the point on the tire where the greatest effect from radial run-out would be found. It is a little more scientific than that but that is the basic concept. There would be a corresponding mark on the wheel from the wheel manufacturer indicating the point where the least effect from radial run-out would be found. Aligning these two points served to reduce the effect of total radial run-out on the wheel and tire assembly and served to improve the vehicle's ride. The balance was then taken care of by dynamically balancing the assembly. This process was something that was primarily used by the car manufacturers when installing tires on wheels at that factory. I am not aware that it was ever something used afterwards by the retail tire industry but I haven't been in it for a long time.
The dot that indicated this point on a tire was red. As I recall red was used uniformly by all tire manufacturers to indicate this radial run-out point.
A second dot was used to indicate the static lightest balance point of the tire. It was intended to be aligned with the static heaviest point of the wheel as outlined above. As I recall there was no uniformity amongst the tire manufacturers as far as the colour used to indicate the static lightest point of the tire. I remember most commonly seeing white or yellow dots however.
If there were both a red dot and another colour dot the protocol was that the red dot took precedence and is to be aligned with the corresponding point on the wheel if it is known. On many car rims received new with the car from the factory this point was indicated. If it was not known then the non-red dot was to be aligned with the valve. After either method the wheel and tire assembly was then dynamically balanced.
If there is only a red dot this was for the radial run-out and the static lightest point of the tire has not been indicated. Best practice is to align the red dot with the heaviest point of the wheel but this does not necessarily achieve a superior balance as this is not its function.
Again, all of the above is what I remember for car tires. I have no idea if motorcycle tires follow the same regiment. Research will tell you that I guess.
