"Tire Wear vs. Traction" Discussion

Hello, Ladies and Gentlemen. I've been dropping by the BeamNG forums since 2014, but only until recently had I purchased it and registered here. This is my first actual post, so I hope that I had posted in the right section.


ON TOPIC:
I've seen that a while back, some people in the "Update Speculation Thread" were discussing tire wear and traction, and from my understanding, most of you are saying that traction would decrease as tire wear increases. I have to say that I disagree with this theory.

When a tire is worn down, its tread will decrease as the wear gets worse. So the tire's contact surface area will increase as the wear goes on. With the slight increase in contact area, shouldn't the traction slightly (unnoticeably?) increase instead? Maybe there's bigger science in this, I don't know. Maybe rubber would somehow react to the heat and get a decrease in efficiency?

I know that many people misunderstand the treads as where the tire's traction comes from, (and I did too a long time ago) and that is incorrect. The tires treads are used on street tires as on wet surfaces, these treads can channel the water underneath the tire out, and keep the tire's contact points dry. Bald tires are dangerous on wet roads since they can no longer channel the water under them away, and this would make them float on the water, losing all traction. Track cars (aside from the dirt ones) don't have treads since most of the time they are racing dry environments, so they need all of the surface areas for more grip. There are treaded "rain tires" if the condition is wet.


So, what is your take on this topic? I would like to hear them.

Sincerely.

 

I disagree, especially when adding water to it. Im sure you can guess why. Race tires, or slicks are a stickier compound, thats why they have so much more traction with no grooves. When there is no tread on normal tires, they get harder and stiffer (less sticky) and wont like to stay planted as much. Harder the tire, The less grip. Thats why when offroad you lower the tire preasure, so you get more surface area and grip.

https://www.reddit.com/r/explainlik...j/eli5_why_race_car_tires_have_more_traction/
http://auto.howstuffworks.com/tire-traction1.htm

 

Thanks for stating your opinion. I had never put the stiffness factor into the equation. I should look more into that.

 

This is a prime example of how standard road tires lose grip after excessive wear. I've felt this myself, not nearly to this extent but I've felt the lack of grip on worn tires vs brand new ones.

Slicks are a whole different ball game like mentioned already.

Also the guy in the video is not too bright because he thinks it's the car and not the worn out tires... Scary that people like that share the road with us.

 

Thanks for all those who took the time to do the voting, and to write up an respond. You see, I didn't do enough research before putting this up, I only thought of it based on what I know. So I probably got it all wrong.

I did try to look up if tires get stiffer the more they are worn down based on what "(GNG) [S.PLH] wearyNATE15" had said, but I have no luck finding any proof (wrong search method, I suppose). So it will be very useful if someone could post some tables here. I am also very interested in where you learned your info.

I'd appreciate any input.

 

Ive thought of this myself actually... treads get worn down and your left with pretty much racing slicks! Right? I guess not because in F1 they use completely slick tires and even they wear? Same with NASCAR and Clio Cups... So I would have to respectfully disagree with you.

-edit-

Sure slicks provide the most traction in dry conditions but if you have slick tires and your driving in the rain... lets hope the car your driving has ESC or something. If you know, F1 and a lot of other racing series have separate tires they use for wet conditions. Wet tires have treads on them to move water from under the tire so the tire can get the most grip possible. In F1 there are 2 different types of wet tires... Full Wets and Intermediate.

 

Basic chemistry and physics. I play disc golf and they make discs out of many different compositions of plastic, some are rubber. Some are really tacky, others are more firm and slick. Now apply that to tires, if you have ever been go-karting you may have had an opportunity to feel the slicks and possibly compare that to road tires on a car.

The slicks are softer and, especially when hot, stickier. Now road tires become more grippy at temp too but they rely on the tread design to keep a lot of the grip.

Another analogy is think of your shoes. Have you worn the soles smooth? If so did you get more or less traction compared to when they were new?

 

I have no tables to give, just personal experience...

You are both correct and incorrect at the exact same time. I know that doesn't make much sense, but if you remove the tread, grip can be better OR it can be worse... It all depends on the conditions.

If you take a set of new tires with perfect tread and drive like a normal member of society, it can take years to wear the tread of a tire. If your daily commute is less than 5 miles (like mine) then you can start getting up into the better part of a decade before the tread on your tires becomes low. I have been driving my car for 9 years now and still have better than 3/4 tread on the tires.

When tires get this old, the rubber starts to degrade some... it gets stiff and starts to crack. This is usually referred to as dry rot as I am sure you already know. A dry rot tire will have nowhere near the traction of a new tire, even if it has better treads left on it. This is because an old tire doesn't flex as well as a new tire.

A tire gets its traction from being able to flex into irregularities in the road. This maximizes the surface area that is in contact with the road and enables better traction. An old, non flexible tire can not flext into those irregularities in the road as well as a nice new tire. This will naturally reduce the grip available right off the bat.

Now... if you took a nice, new, flexible tire and physically cut the tread off of it, it would have better grip on a perfect road or a race track, again, under the right conditions. Like the dry rot and flexible rubber comparison, the slick and treaded comparison with the same flexibility of rubber will suffer the same issue without treads. The treads allow chunks of rubber to move independently from each other filling irregularities in the road easier than a tire with no tread at all. A tire with no tread at all will be unable to flex as well into those holes and thus will have reduced traction.

Finally we come to compound. The reason that race tires are so sticky is because they want to maximize their surface area in contact with the ground and so that the rubber is flexible enough that the tire can fill the irregularities in the pavement without using treads. Cold racing tires, as you may know, can not flex as well as warm tires, and this causes many crashes that you end up seeing within the first few corners of a race at times. This is because of their lack of ability to flex when they are cold. Once warm, race tires can be as sticky as some glues.

Now, I wrote that, I made it sound as though tire grip is all about surface area. In reality, Surface area is only in it to decrease the forces that are being applied to the rubber. The more rubber that is in contact with the pavement, the lower the forces being applied to the rubber overall. If it was impossible to shear rubber, no matter the force, you could get the same amount of traction out of a formula one tire as a bicycle tire with the same amount of downward pressure on it. This is because of the frictional force equation, Ff = u*N. Notice, there is no area anywhere in that equation. Just a downward force N and a Friction Coefficient u.

 

Absolutely right. Btw: in addition to the guy above me I would add the point of uneven tire wear

 

"Another analogy is think of your shoes. Have you worn the soles smooth? If so did you get more or less traction compared to when they were new?"

Actually about that. I wear dress shoes and these ones (which I've been wearing for 1-2 month) had no treads on it. (Yes, it do look a little worn, but it has no treads out of the box).
I have an explanation for that: "Static Friction". No treads maximize the surface area and get the maximum friction on dry conditions. I am not welling step onto wet surfaces with these since they cannot push the water away as good as the treaded ones.

And I still have to say that treads on street tires don't have much do with gaining traction under dry conditions, as they are designed to channel out water. The treads on dirt racing tires would be very useful as they are going on uneven surfaces. Their treads are designed to grab onto the unevenness of the terrain for maximum efficiency.

I do agree that track racing tires use different rubber, and they have superior grip.

Image reference: https://ka-perseus-images.s3.amazonaws.com/611e9ac25351f8af8f05a4bc0668c792f3dbc0f4.jpg

As for the fact that rubber get's stiffer overtime and starts to lock up, I have to agree with that as well.

Anyway, these are what I think personally, and it could still be incorrect.

 

When I posted, I forgot to put that the warmer the tire, the stiffer. Whoops

"Consumer tires have far less traction when "bald" usually due to heat cycling, and the fact the the compound at that level is often different than the compound at the surface when a tire is newer. Heat cycling is essentially the hardening of the rubber each time the tire warms up and cools down. The harder the tire, the less grip."

https://www.reddit.com/r/explainlik...j/eli5_why_race_car_tires_have_more_traction/

 

Thank you!

The Heat Cycling does make sense. That was the missing piece of the puzzle. I get it now.

There's a post waiting for moderator's approval at the moment.

 

I'm honestly surprised nobody here has put personal experience in yet.

My experience and that of many others is that a worn tire has less traction, even in the dry, yes it's smoother but the treatments used to give the material its road going properties are also heavily abused, I currently have almost no front traction wet or dry compared to when I bought the car.
Previous vehicles I've gone through complete sets of tires brand new to replacement again. As wear goes up, grip goes down. My focus wagon had worn front tires but not rear, the difference in handing from swapping axles over was remarkable

 

You're correct in that the original design plays a role. You design something smooth like dress shoes and it should be able to have traction under the conditions it's designed for. That said you take something designed to have traction with grooves and then you remove them you may see a loss of performance not necessarily because of the loss of the tread but because in the process of removing it you damaged the material or the material underneath it is of a different composition and not up to the task of providing grip.

Your dress shoes are more like slicks, my work boots are more like everyday tires and my hiking sneakers are more like off road tires. Different styles for different purposes.

 

Or even when you wear down the shoe, it loses grip and on certain conditions you will fall