Scirocco Central

Hi,

this week I was assembling new tires on my car. Today I was looking and found that they don't follow the rule of the red/yellow dots (that we have on the tire) to achieve a better balancing.
Now I don't know what to do. Shall I go there and disassembly the tires, doing all the process again? What is the real impact of this "mistake"? Am I just overestimated this point? I don't detect any vibration on the steering wheel at this moment.

Thanks (and an Happy New Year).

As long as the wheel / tyre assembly is balanced ir doesn't make any difference. As you say the markers make it easier to balance utilising less weight / weights. Sadly, few tyre fitters.seem to know the purpose of the markers.

And we should use the red or the yellow dot as reference to the valve steam? I read already 2 opposite ways and in my car fortunately the placed 2 tires with the yellow dot near the valve.

First you need to understand exactly what the dots signify . Different tyre manufacturers use different colours to signify different things, as do different OEM's.

At Landrover , a white dot signifies the assemblies 'high point' - note that i stated assembly . ie the tyre mounted on the wheel. The white dot is always at 12 o'clock when the assy is mounted to the car . The idea being that as the wheel sits on the studs , the weight of the wheel brings it down and lessens the effect of the 'high point' . By high point - i am referring to RFV (radial force variation) , the assemblies tendency to rotate eccentrically.

A yellow dot , signifies the tyres conicity ( all tyres are cone shaped as a result of their construction and manufacturing process - this is why when you roll a tyre along the ground , it veer's off to the left or the right) , the yellow dot should always be placed toward the inside.

A blue dot , signifies that the assembly has been inflated to transit tyre pressures. The transit pressure ( between 50-55psi ) is used whilst the vehicles are being shipped around the world , or stored on the parking lot - this reduces the chances of 'flat-spotting' . Prior to sale the tyres pressured are lowered to normal road pressures as part of the PDI.

Some of our tyre manufacturers use red dots ( like Bridgestone ) this signifies the high point of the tyre . We disregard this , as its more accurate to measure the wheel & tyre assy as a whole - hence the white dot.

Like i've stated , the significance of the different coloured dots will vary between different tyre manufacturers , and also between different vehicle manufacturers. You will end up tying yourself in knots trying to do the best thing , by deciphering these codes - so the best thing to do is ignore them.
The important thing is to make sure what you've got is as accurately mounted as possible.
Just make sure that who ever fits your tyres to your wheels 'match mounts' them (if they have the equipment) to minimise RFV , and balances them fully . If they can mark the (RFV) high point of the assy , then site this at 12 o'clock when fitting to your car.

Lee

Those are Yokohama tires and have the red and yellow dot.
In my case, 2 of the tires have the yellow dot near the valve, one tire the red dot at the valve position and the other one both dots far away from the valve.
The 2 cases with the yellow dot near the valve have 30g and 45g weight added. The one with the red dot in position, has 20g added. The remaining tire has also 20g.

Sincerely I don't know if 45g is an acceptable value or if we could reduce the weight rotating the tire on the wheel. I just don't understand why they didn't take care of following this dot rule (if they know it).

uklee wrote:The white dot is always at 12 o'clock when the assy is mounted to the car

Don't understand that, it will be at 12 oclock until it first turns then it will likely never stop there again. What is the significance of 12 oclock except for when it first goes on the car?

chelspeed wrote:

uklee wrote:The white dot is always at 12 o'clock when the assy is mounted to the car

Don't understand that, it will be at 12 oclock until it first turns then it will likely never stop there again. What is the significance of 12 oclock except for when it first goes on the car?

Exactly that - its only used when mounting the wheel to the car .
The white dot is located adjacent to the 'high' point of the wheel & tyre assy ( i.e where the assy is at it's most egg shaped ). When you mount the wheel on the hub , there is always a bit of slack between the holes in the wheel and the wheel bolts .By having the dot at 12 o'clock when you mount the wheel , the wheel naturally 'hangs down' on the studs - so this slack is taken up and effectively brings the high point 'inwards' - this helps to negate the effect of the high point.

Lee

Twiki wrote:Those are Yokohama tires and have the red and yellow dot.
In my case, 2 of the tires have the yellow dot near the valve, one tire the red dot at the valve position and the other one both dots far away from the valve.
The 2 cases with the yellow dot near the valve have 30g and 45g weight added. The one with the red dot in position, has 20g added. The remaining tire has also 20g.

Sincerely I don't know if 45g is an acceptable value or if we could reduce the weight rotating the tire on the wheel. I just don't understand why they didn't take care of following this dot rule (if they know it).

45g is fine , you may reduce or increase the weight by match mounting - each wheel & tyre combo is different. If there is no vibration then i wouldn't get my knickers in a twist over 45 grams.

You need to be careful that you are not confusing mass with force .
MASS is dealt with by adding weight in order to achieve balance. The wheel will have a concentration of mass ( it's heaviest point ) which many people think will at the valve (it's not always !) , as will the tyre ( the point opposite the heaviest part of the tyre is marked with a yellow dot than that i can be mounted adjacent to the heaviest part of the wheel) .It makes sense to line up the heaviest part of the wheel opposite the heaviest part of the tyre , but Dependent on where the heaviest point of the assembly is , the corresponding amount of mass (weights) are added to achieve balance.
FORCE is different , Wheel & Tyre assys are affected by whats called RFV (Radial Force Variation - google it !) having high RFV in your W&T assy is far more likely to create vibration than poor balance. So the RFV (red dot) always takes precedence when 'match mounting' . With 'match mounting' you can lower the W&T assys overall RFV by opposing the highest point on the wheel (NOT the heaviest) with the highest (NOT the heaviest) point on the tyre . This is 'high point' is then further negated by having it at 12 o clock when mounting to the hub .

Tyre stiffness also plays a significant part in RFV , but discussing that is beyond the bounds of this enquiry

Lee

Excellent write up here Lee, this is very useful info. This just proves how 'scientific' tyres are, especially when taking into account balance, camber, tracking and all that kind of stuff.

Amazing amounts of engineering and research goes into these 'black and round' objects on each corner of the car.

Thanks for your input!

skippy wrote:....Amazing amounts of engineering and research goes into these 'black and round' objects on each corner of the car....

Like you wouldn't believe mate ! - i deal with the engineering side of wheels / tyres / suspension geometry all day long as part of my job , and the most common 'faults' i come across are simply due to peoples misconceptions . A 'little' bit of knowledge can be a dangerous thing !

Lee