[Surferdude]

Hi all,
At my request the mods have graciously begun this thread as I felt the ongoing questions about tyres indicate a clear concern about getting the best out of thes expensive little pieces of rubber and steel which are fitted to our cars.
Rather than bore you all with a "start from scratch" , Tyres 101  I've elected to jump around a bit. This particular topic will contain random information about tyre technology which I hope will be interesting for some of you.
I'll probably start a separate topic for queries. Obviously you can lodge questions here about anything I post up but I feel it may be useful to have a separate topic specifically for your queries. Look for it under some fancy and original name like "Dear Dorothy Dix" (Dear Trev).

I can't stress the importance of tyres enough.
What part of the car do you think is most important. People often say, brakes or steering or shockabsorbers.
My argument is that, if you have a flat tyre, none of the above will be of any use to you.
Perhaps the most important part of any car is the driver (and the steering wheel in his hands).
Tyres, brakes, suspension, steering, shocks are all important as an integral unit.

So, to scrimp on tyre selection is reducing the effectiveness of every other component and seriously detracting from the safety of all occupants and other road users.

Here's a couple of pics taken through a glass plate set in the road, demonstrating how tyre treads work in the wet.
Both are of directional tyres.
Can you see the difference in the water flow and why one might be better than the other?

[Dazzler]

Thanks Trev (a good start)

I assume it is the 2nd photo where the tyre is throwing the water out to the sides?

[whitbomb07]

Trev

Nice post.

I'm keen to see what you think of rubber vs silica tyres.

Regards

Daniel

[Mutley]

Keen to hear your thoughts on different compounds and silica too.

[Surferdude]

Silica isn't an alternative to rubber. It is an additive which improves the qualities of tread rubber.
It adds to the cost. There are degrees of silica additive.
ie. You can add a little bit and call it a "silica based tread" but the improvement will be minimal. Rigorous testing is required to determine what percentage is optimum for any given tread and carcass design.
The better quality brands will cost more because of this testing and the amount of silica they add.

Incidentally, the modern tyre has only a small percentage of natural rubber in it. Most of the components are oil based. From memory it takes about 8 litres of oil to make one car tyre. Not exactly an eco friendly product.

That's the simple answer.


Below, for the technical of you is a transcript from several slides I used to explain in detail the whole rubber compounding process.

History of Rubber Industry
   South American Indians used latex to make rubber balls
   Latex was used to waterproof cloaks
   Rubber was mixed with fillers and dissolved in solvents and spread on fabric rain coats
   Vulcanisation discovered by Charles Goodyear  1839
   John Boyd Dunlop developed pneumatic tyre  1888
   Natural rubber plantations developed in Southeast Asia
   Germans develop synthetic rubbers between the wars
   Rapid development of synthetic rubber in USA during the war


What is Rubber?
   A long chain polymer
   Elastic - able to be stretched up to 500% or more
   Capable of being vulcanised
   Naturally occurring and man made
   Used in a wide range of areas, hose, window seals, conveyor belts, tank linings etc
   The properties of the rubber product are determined by the polymer used and the additives

Natural Rubber
   Extracted from trees in form of latex.
   It has also been extracted from Guayule and dandelions
   Plantations in South East Asia
   Used in latex form for gloves condoms etc
   Good general purpose rubber not resistant to oils
   Good resistance to cut and chip
   Reasonable tread wear
   Reasonable heat build up properties
   Reasonable wet grip


Synthetic Rubbers
   Produced from oil
   PBD  Poly Butadiene
   Excellent tread wear
   Poor wet grip
   Poor cut and chip
   Low heat build up
   SBR Styrene Butadiene Rubber
   Good tread wear
   Reasonable wet grip
   Reasonable cut and chip
   High heat build up


Carbon Black
   Manufactured from oil
   Reinforces synthetic rubber to provide improved tensile strength
   Increases rubber hardness and tread wear
   Particle size controls properties
   Up to 5 different types used in a tyre which result in changes to the following

•   Hardness
•   Tread wear   
•   Heat build up   
•   Rebound      
  
Rubber Additives
   Waxes: Provides protection in storage
   Antioxidants: Protects against weathering in service
   Antioxidants: Protects against Ozone attack, deep cracks.
   Oils:   
   Reduces cost of rubber
   Reduces hardness
   Improves processing in plant
   Sulphur: Vulcanises rubber
   Accelerators: Speeds up the rate of vulcanisation
   Activators: Speed  up rate of vulcanisation
           (Zinc Oxide & Stearic Acid)


Tread Compounds
•   What’s in a tyre?
   The traditional formulation would include: synthetic rubber, carbon black and other materials.

•   What is the major development in compounds?
   The introduction of a silica blend compound which has provided a substantial improvement in wet grip, and improved wet adhesion and durability.

   The amount of silica in the tyre determines its high performance capabilities. Eg: High Performance tyres have a very high % of silica blend and have excellent wet weather performance.


Rolling Resistance
•   Energy is required to rotate the tyre. The lower the rolling resistance the less energy that is required.

•   The construction, tread pattern and tread compound all have an impact on the rolling resistance of the tyre and therefore the fuel consumption of a vehicle

•   Improved rolling resistance is achieved by:
      -the type of tread compound used
      (eg: silica blends: high performance carbon blacks)
      -use of lightweight materials
      -highly developed building technique


What is silica?
   Comes from a very fine sand material.(Silicon Dioxide)

    Technology now exists to blend with tread compound formulations.

    Has redefined wet grip/dry grip/wear compromise.(Controlling Hysteresis)

Silica Technology
•   
As a tyre rolls over the road surface, which is not smooth, the tyre surface strikes irregularities which result in a bounce or rebound process, if this process is of a high magnitude, rolling resistance increases and grip, mainly wet starts to decline.

•   The use of SILICA and a coupling agent allow a much more controlled bonding to take place with the rubber and carbon black….This results in a compound which has a more stable modulus and hence more controlled rebound, it also stabilises the compound for a longer period resulting in stable properties for the life of the tyre.

[Surferdude]

Thanks Trev (a good start)

I assume it is the 2nd photo where the tyre is throwing the water out to the sides?

Yeah. It is. Also, notice how there's a solid wall of water across the front of the tyre in th efirst pic, whilst in pic 2 you can see a V of almost clear road for the tyre to work on.
On a non-directional tyre, the wall of water across the front would be much worse still.

[Lakes]

Trev thanks interesting post!
what i worry about is if i went for a wet weather tyre, then found we had a drought and i never got to test what it felt like.
when i was young, i raced sprint Karts ( go Karts ) on sealed race tracks not dirt. we ran slicks ( no tread at all ) if it rained there was no grip at all they just slide all over the place and you had to drive really careful if it started to rain. if you used wet weather tyres this helped when it rained but they had less grip if the track dried out.
also from years of driving i've had tyres that had deap tread or open tread patern that seemed to what i'd call Squirm in steering.
Trev how whould you tell if a tyre would have more tendancy to have a squirm effect in steering because of treat design?
thanks Lakes

[Surferdude]

Trev thanks interesting post!
what i worry about is if i went for a wet weather tyre, then found we had a drought and i never got to test what it felt like.
when i was young, i raced sprint Karts ( go Karts ) on sealed race tracks not dirt. we ran slicks ( no tread at all ) if it rained there was no grip at all they just slide all over the place and you had to drive really careful if it started to rain. if you used wet weather tyres this helped when it rained but they had less grip if the track dried out.
also from years of driving i've had tyres that had deap tread or open tread patern that seemed to what i'd call Squirm in steering.
Trev how whould you tell if a tyre would have more tendancy to have a squirm effect in steering because of treat design?
thanks Lakes

If you know what to look for in a tread pattern it becomes pretty obvious if a tread will squirm. Look for blocks or patterns which are either obviously self supporting or joined by small bars or bridges between them. If the blocks are free standing or extremely fine they'll flex and squirm as the tyre rolls along the road.
You have to picture the footprint which, with the weight of the car on it is a distortion of the tread pattern if you look at it from the top.
Firstly and IMO most importantly, you need a solid centre rib which will help to stabilise the whole footprint and also give you good directional stability at highway speeds.

Here's a pic of a tyre with a solid centre rib.



But it doesn't have to be as basic as that. This one has "Sipes" in the rib to help traction and grip.



Or this directional one which also features very firm self supporting rib type blocks all the way across the tread.



Free standing blocks like the following two will move around or squirm, although the second one will be better than the first





Now, looking at the above pics you can also see how the shoulder area can wear rapidly or erratically if it isn't well supported. For instance on the second bottom pic, hard cornering or incorrect wheel alignment will accentuate shoulder wear dramatically.
On the directional tyre you can see how substantial the shoulder blocks are.
Of the top two pics the first one has a better shoulder design becasuse the blocks are tied into a solid rib just before the first circumferential channel, whereas the second one has shoulder blocks which pretty much have to depend on themselves for support. And remember the shoulder is the hardest working part of a tyre.

[Dazzler]

Gr8 lesson Trevor (very logical) he says heading down stairs to look at the tyres on his i30 and Tiida...

[Surferdude]

Something I saw in another thread/ topic reminded me of some of the crazy things customers have said to me over the years.
It occurs to me some of you may find them as entertaining as I did at the time and many times since....

1/ A few months after Allan Grice drove the Bathurst 1000 in a Commodore with Yokohama sponsorship one of the local lads approached me in our Toowoomba store and wanted a set of Yokohamas the same as Allan Grice "drove Bathurst on". There was no way I could convince him he ran slicks at Bathurst as all cars did by then. He just wouldn't have it and eventually left the store muttering under his breath.

2/ On more than one occasion I asked people what sort of car they had only to be told they didn't know. On one memorable occasion the lady earnestly informed me that it was a red one. (I'll swear on the Bible to this).
Don't ask what colour her hair was when she came in.

3/ Another (older) lady stormed into the office as the guys were changing her tyres and demanded to know why they weren't replacing the "metal bits in the middle" as well. She was convinced we were trying to rip her off by only doing half the job (using her existing rims).

4/ Guy came in to me very early in my career and told me his mechanic had informed him all his tyres were faulty as the treads were stretching.  Some of you may not be aware that, in order to reduce tyre noise, all tyres feature tread blocks of different size in a sequence around the tyre. Like this



You'll notice that each tread block is slightly larger than the one beside it. In most tyres, the cycle is about 7 blocks (depending on the size of the blocks). Check your tyres, you'll see thsy all have it. Anyway, this guy's mechanic had told him because the tread blocks were different sizes, they were stretching.

5/ Similarly, every tyre has Tread Wear Indicators (TWIs) which are small ridges of rubber across the tyre in the base of the tread grooves - several times around the circumference of the tyre. These are marked on the edge of the tread where it joins the sidewall with the letters "TWI". When the tread wears down to the point where it is the same height as the TWIs, the tyre is no longer legal.
But this driver's mechanic (not the one in 4 above) had told him his tyres were faulty because there were little bubbles in the base of the tread. And it was really serious because all the tyres had them.

There are plenty more stories but these five spring to mind every time someone mentions the "lack of intelligence" (or words to that effect) displayed by customers.

[Dazzler]

Gr8 stories Trev.. I have similar ones from some of my many jobs.. (I must share some day)

[Surferdude]

Maybe we could get up a night club act.
"Trev the Rev and Daz from Taz"

[Surferdude]

Some Wet Road Facts

1/  At 100kph we travel 27.7 meters/ second
2/  In 2mm water,a 195/50R15 tyre must clear 7 litres of water per second
3/  In 2mm water, a new tyre contact area reduces by 20% at 100kph
4/  In 2mm water, a tyre with only 1.5mm tread remaining reduces contact area by 85% at 100kph
5/  If the water depth increases to 4mm the 195/50R15 tyre must clear 14 litres of water per second to retain road contact.

These images are from an old counter card developed by Goodyear. I think they speak for themselves

[Lakes]

that's good Trev!
Would call that aquaplaneing at speed, wider tyres will do that more than narrow tyres.
i've had cars auaplane on corners and slide forwards instead of steering around the corner, a light touch of the brake puts weight on the front tyres stops them Aquaplaneing & you get the steering back. that was on rear wheel drive car.
have never felt that in the i30 in rain yet, but if you use the Torque on corners when it's raining the i30 breaks traction easy so have to take care. but i back off if i feel it loose traction and it regains grip again fast.
i learnt throtle control from racing sprint Karts, they only have one disc brake on the rear axle ( one peice rear axle ) so on tight corners you actually steer with the throtle. but thats another story.
cheers & thanks again Trev good post.

[Surferdude]

that's good Trev!
Would call that aquaplaneing at speed, wider tyres will do that more than narrow tyres.

Quite right Lakes.
The narrower tyre penetrates the water better and pushes up less of a bow wave than a wide, low profile tyre.
Works the same in snow - look at the snow tyres on the WRC cars in Sweden. Apart from the studs the tyres are narrower to push through the soft top of the snow.
And also in mud. I saw a guy absolutely blitz the field in a rally with a little underpowered Mazda years ago on the Darling Downs. It was wet, muddy and nighmarish but he turned up with some standard wheels and very narrow rally tyres he'd scrounged from somewhere. Blew everyone away.
Wide is good - when it's dry.

[2i30s]

this may be unrelated to anything posted till now but here i go.    is a semi slick street legal tyre any good in the wet and also are they a truly street legal tyre? 

[Dazzler]

this may be unrelated to anything posted till now but here i go.    is a semi slick street legal tyre any good in the wet and also are they a truly street legal tyre? 

Here's a Chichen and Egg question.. Did you post that question because you saw Trev is back on or... did Trev just happen to feel he was needed...

[2i30s]

a bit of each mate.    but then i realised he's in the UK [the,conected to british telecom coment] I'm in no hurry for an answer. some one else may make a comment on the matter. 

[Surferdude]

Hi guys,
sitting in a services N of Edinburgh but S of Aberdeen at present.
Hope to catch up with Brian tomorrow for a coffee.
In the meantime, I am not sure about the above question except that I don't think a grooved slick is legal reagrdless but don't quote me on it.
It would ceratinly not be the best in real rain on real roads. After all, race tracks are designed for those types of tyres, highway type roads are intended for road vehicle sand normal road tyres so there would certainly be some circumsatnces where the grooved slick would not be the best.
BTW. Driving a 1.4 Vauxhall Corsa.
On Continentals. Report to follow in a week or so when we get to Canada where I'll have regular internet access at our son's house.
Over and out.
 

Trev