Coloured dots and stripes - whats that all about?
When you’re looking for new tyres, you’ll often see some coloured dots on the tyre sidewall, and bands of colour in the tread. These are all here for a reason, but it’s more for the tyre fitter than for your benefit.
The dots on the sidewall typically denote unformity and weight. It’s impossible to manufacture a tyre which is perfectly balanced and perfectly manufactured in the belts. As a result, all tyres have a point on the tread which is lighter than the rest of the tyre - a thin spot if you like. It’s fractional - you’d never notice it unless you used tyre manufacturing equipment to find it, but its there. When the tyre is manufactured, this point is found and a coloured dot is put on the sidewall of the tyre corresponding to the light spot. Typically this is a yellow dot (although some manufacturers use different colours just to confuse us) and is known as the weight mark. Typically the yellow dot should end up aligned to the valve stem on your wheel and tyre combo. This is because you can help minimize the amount of weight needed to balance the tyre and wheel combo by mounting the tire so that its light point is matched up with the wheel’s heavy balance point. Every wheel has a valve stem which cannot be moved so that is considered to be the heavy balance point for the wheel.
As well as not being able to manufacture perfectly weighted tyres, it’s also nearly impossible to make a tyre which is perfectly circular. By perfectly circular, I mean down to some nauseating number of decimal places. Again, you’d be hard pushed to actually be able to tell that a tyre wasn’t round without specialist equipment. Every tyre has a high and a low spot, the difference of which is called radial runout. Using sophisticated computer analysis, tyre manufacturers spin each tyre and look for the ‘wobble’ in the tyre at certain RPMs. It’s all about harmonic frequency (you know - the frequency at which something vibrates, like the Tacoma Narrows bridge collapse). Where the first harmonic curve from the tyre wobble hits its high point, that’s where the tyre’s high spot is. Manufacturers typically mark this point with a red dot on the tyre sidewall, although again, some tyres have no marks, and others use different colours. This is called the uniformity mark. Correspondingly, most wheel rims are also not 100% circular, and will have a notch or a dimple stamped into the wheel rim somewhere indicating their low point. It makes sense then, that the high point of the tyre should be matched with the low point of the wheel rim to balance out the radial runout.
What if both dots are present?
Generally speaking, if you get a tyre with both a red and a yellow dot on it, it should be mounted according to the red dot - ie. the uniformity mark should line up with the dimple on the wheel rim, and the yellow mark should be ignored.
Interesting stuff, Steve & Andy - thanks for bringing it up
I can just see everyone heading out to their cars, crawling round on all fours, feeling for dimples on the rim to see how the tyres have been mounted … with a big queue at Kwik Fit in the morning
Exige wheels are terrible for balancing as they are already buckled as standard …
I would have to disagree with you here. My opinion would lean towards the fact that there is no weight over the front end of an exige/elise so any slight imbalance in the wheel will be quite noticeable. There are other factors to also take into consideration, tyre wear, pick up on the tyres, etc, etc. The set of fronts on my car have had to be done twice through the course of their life so far (not much left on them now).
If a wheel is buckled you will be very hard pushed to see it while it is still on the car unless it is badly bent. Deviation upto 3-4mm you will need to place the wheel onto a balancing machine and spin it up. The human eye is far more acurate than you cpould possibly imagine and even the slightest dink can be notice with ease. Saying that though, a good tyre balancer will be able to balance and bent whell within a certain amount.
You need a place that has decent equipment but also a guy who understands or rather has the patiance to take weights off as well as on during the process which can take quite some time as dynamic balance often creates a shifting of the problem so you end up chasing your self - or give up.
Correct. It is a fine art balancing a tyre and as you say can take some time to be done correctly. Someone who knows what they are doing will only apply one lot of weights and then will pain stakingly re-distribute them around the rim to find the perfect balance. You should never really see anymore than 30g at any one point.
For those that track their cars - I’ve had issues with flatspotting 48’s. My last set got pretty well knackered by the time I gave up on them - had a terrible shimey at speed that balancing wouldn’t take care of.
Sorry mate - but they are - I had a big discussion with my tyre place and we put up all 12 of my wheels - he was convinced I’d kerbed half of them … and 4 were a brand new set.
I have one rear that is almost impossible to balance its so bad.
In contrast my Speedlines have hardly any weights on at all …
Has anyone found the dimple on a standard Exige S1 rim? I have looked & gave up - it must be very a subtle mark. Can someone share a picture?
The irony is that while Yokohama 39’s and 48’s do use yellow dots to mark the light spot and red dots for the “uniformity high points”, my sets of Yoko slicks and rains don’t have any dots!
Coloured dots and stripes - whats that all about?
When you’re looking for new tyres, you’ll often see some coloured dots on the tyre sidewall, and bands of colour in the tread. These are all here for a reason, but it’s more for the tyre fitter than for your benefit.
The dots on the sidewall typically denote unformity and weight. It’s impossible to manufacture a tyre which is perfectly balanced and perfectly manufactured in the belts. As a result, all tyres have a point on the tread which is lighter than the rest of the tyre - a thin spot if you like. It’s fractional - you’d never notice it unless you used tyre manufacturing equipment to find it, but its there. When the tyre is manufactured, this point is found and a coloured dot is put on the sidewall of the tyre corresponding to the light spot. Typically this is a yellow dot (although some manufacturers use different colours just to confuse us) and is known as the weight mark. Typically the yellow dot should end up aligned to the valve stem on your wheel and tyre combo. This is because you can help minimize the amount of weight needed to balance the tyre and wheel combo by mounting the tire so that its light point is matched up with the wheel’s heavy balance point. Every wheel has a valve stem which cannot be moved so that is considered to be the heavy balance point for the wheel.
As well as not being able to manufacture perfectly weighted tyres, it’s also nearly impossible to make a tyre which is perfectly circular. By perfectly circular, I mean down to some nauseating number of decimal places. Again, you’d be hard pushed to actually be able to tell that a tyre wasn’t round without specialist equipment. Every tyre has a high and a low spot, the difference of which is called radial runout. Using sophisticated computer analysis, tyre manufacturers spin each tyre and look for the ‘wobble’ in the tyre at certain RPMs. It’s all about harmonic frequency (you know - the frequency at which something vibrates, like the Tacoma Narrows bridge collapse). Where the first harmonic curve from the tyre wobble hits its high point, that’s where the tyre’s high spot is. Manufacturers typically mark this point with a red dot on the tyre sidewall, although again, some tyres have no marks, and others use different colours. This is called the uniformity mark. Correspondingly, most wheel rims are also not 100% circular, and will have a notch or a dimple stamped into the wheel rim somewhere indicating their low point. It makes sense then, that the high point of the tyre should be matched with the low point of the wheel rim to balance out the radial runout.
What if both dots are present?
Generally speaking, if you get a tyre with both a red and a yellow dot on it, it should be mounted according to the red dot - ie. the uniformity mark should line up with the dimple on the wheel rim, and the yellow mark should be ignored.
I’ve queried several tyre fitters about this, and nobody so far knew these facts. Go figure
Fortunately I’ve finally found a place where they know what they’re doing up here, perfect balancing: Checkpoint in Aberdeen
Andy, I would have taken them back mate and played ‘Mary-hell-up’ demanding a round set…No wheel is 100.00% perfectly round but they should not be out by the amount your talking about and certainly not visible.
I’ve queried several tyre fitters about this, and nobody so far knew these facts. Go figure
Tell me about it, it not just tyre fitters either!! The amount of workshops I visit where you know more about the job than what the guy behind the desk does… Makes you want to jump over the counter and tell him to get out of the way while you do it yourself… Very annoying and testing on the nervses, especially the types of businesses some of these guys are running… Scary!!
To be quite honest I have never heard about the dimple on the rim. I was u nder the impression the dot gets aligned with the valve.
Finally sorted! After the third trip to my local national tyres one both tyres showed a 5g inbalance. Ive built up a good rapour with them over the last few years so generally trust them aslong as they dont let any of their ‘monlkeys’ near my car! This is the first and hopefully the last time i have problems with them.
Cheers For all the help
Gav