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Recently, i had a discussion with someone about tire width. I claimed, that with bigger (wider) tires, a car would have more traction/grip. The person i was discussing this with, agreed with me, up to a certain point. He said, that if the tires were too wide for the car, the opposite would happen, less traction/grip. He also claimed that the chance of aquaplaning would be higher.

My thoughts on that were that that mostly depends on the kind of profile of the tire. It seems to me that if the same tire, on another car (fit for that tire width) would provide good traction/grip without increased aquaplaning risk, the same would hold for a narrower tire. I would argue that the traction/grip is a function of contact with the road and thus wider tires equals more traction.

My question thus is: Does having a wider tires (under the same car) provide more traction?

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Well, both of you are correct. In general terms, a wider tire has a greater contact patch with the ground, so can provide traction. As your friend stated, though, the tread pattern/depth will have a lot to do with how the tire performs during inclement whether.

Take for instance a race tire which is rated at a width of 325mm. With your line of logic, this tire would provide excellent traction for the vehicle. And this would be true, unless the tire was driven on the street where there is water. The car would not have the traction needed to sustain type of safe operation.

Take the same 325mm tire and place it on snow. You can expect a loss of traction. In fact, a skinnier tire will work better in snow than a wide tire would. The reason for this (I believe ... no empirical evidence) is because it has more weight per square inch due to the smaller contact patch. It also cuts through to the ground better instead of riding on top of compacted snow.

There are other factors involved here as well. If a tire is made to last longer (say made of harder rubber), it may not have as good of traction as a tire of the same width and softer material. Tread patterns themselves have a play in traction. Side wall height, tire flex, and inflation also have a play in it.

Another area to consider is what is the physical dimensions of a tire will you be able to fit under your vehicle? There is a trade-off here as well. Another trade-off is cost, the wider the tire, the more expensive it will be (all other things being equal).

Unfortunately, there are so many variables when considering traction, you just cannot put a generalized statement upon a single given factor, which is width in your case. To provide the best tire for your application takes research, bringing all of the factors together to determine your best course.

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  • hmm, I didn't look at it that way. Thanks! – DEVries Dec 30 '14 at 8:07
  • A skinnier tire only works better in snow if it can cut through to the pavement. If it can't, then the wider tire will outperform it. This is why a snowmobile will outperform a motorcycle of the same weight and power on snow. – Dr. Funk Jan 5 '17 at 20:33
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    @Dr.Funk - I'd have to disagree with you, mainly because a snowmobile has cleats. It would be like putting chains on a tire. Without the cleats, the snowmobile would just sit and spin. – Pᴀᴜʟsᴛᴇʀ2 Jan 5 '17 at 20:38
  • A snowmobile will outperform a motorcycle with tire chains. Why? Because it has a much, much larger contact area. – Dr. Funk Jan 5 '17 at 20:39
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    Really, if you'd like to talk further about this, we should move it to the The Pistop, Mech's chatroom. You are not taking into account a lot of different factors with what you've written. I'd love to discuss them with you if you have time. – Pᴀᴜʟsᴛᴇʀ2 Jan 5 '17 at 22:15
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Wider tires will give better grip on dry pavement up to a point. Once the tire gets too wide it won't heat up enough to get good grip. Also wider tires will be more susceptible to hydroplaning.

This is why motorcycle tires are just about impervious to hydroplaning. I've ridden my bike in pouring rain at 75 mph with a nearly bald rear tire with no problems. It's an older bike with a 100 mm wide rear tire, a newer bike with a 200 mm rear tire might have problems.

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  • So basically, a thinner tire can "slash" through the water, sort of like a knife, whilst a wider tire traps water under it? Wouldn't the profile of the tire mitigate most of that? – DEVries Dec 31 '14 at 8:07
  • The tread in the tire can help, a lot, but a wider tire still has to push the water further. A bicycle tire is even more resistant to hydroplaning, which is why tread is really unnecessary on a bicycle tire, that plus the fact that hydroplaning speed is above where bicycles typically operate. – Eric Dec 31 '14 at 14:24
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A wider tire does not give more traction because of the width of it. Surface area does not impact friction. Friction is calculated by force of the contact (in this case weight) and the friction coefficient. They use a different compound for the wider tires that require the size, so the sidewalls can support the vehicle. Having a wider tire will increase chance of hydroplaning. You have less pressure with wider tires and it is more difficult to break the surface tension of the water. Here's a link detailing the tire and it's friction. http://www.physlink.com/Education/AskExperts/ae200.cfm

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  • That article is factually incorrect. Wider tires are not necessarily a softer compound. Softer tires do give more grip, but increasing the area of the tire that contacts the road also increases the grip. Imagine an infinitely-wide tire, and trying to push it sideways along the road surface. It wouldn't budge, and that's not due to weight. A narrower tire would provide less resistance simply because it has a smaller contact patch. – 3Dave Mar 26 '18 at 15:50
  • @3Dave well, the article is not totally incorrect. The overall premise is correct, in that since friction is a function of CoF and normal force, as you increase Area you decrease force/sq inch so grip should not change. The reality is that there is a drop in CoF as you increase so there is a 'small' increase in grip as you increase area. This is called 'tyre load sensitivity'. The less grip 'simply because it has a smaller patch' comment seems intuitive but it is just wrong! 'More area = better ability to handle heat and wear so softer compound = more grip' is actually the correct answer. – matt Oct 10 at 4:44
  • @3Dave, well maybe you are being emotional about it. I didn't say that a wider tyre does not offer more grip. It clearly does; I am commenting on your assessment of why it offers more grip. There has been more than enough empirical evidence on this. You gain marginal increase in lateral grip by simply increasing the surface area. There are numerous explanations by engineers online if people are willing to read. In any case your characterisation is way off and the appeal to your own authority is kind of funny. Many of us have had track cars... that's why we are interested in this stuff – matt Oct 10 at 5:00
  • I did not appeal to my own authority, but I draw from my experience as an engineer and as a driver - as does everyone else. Yes, there is a ton of empirical evidence on this topic, and, yes, the linked article is incorrect. I stand by my statements. – 3Dave Oct 11 at 23:54
  • @3Dave you are clearly not an engineer. Otherwise you would not make such terrible mistakes. If you were an engineer, you would know that tyre width does not change the contact area of a tyre, it changes the shape of the patch. Tyre pressure is what affects the size of patch (all things being equal). You would also know that an infinite tyre width would require infinite psi so there would be almost no contact with any surface, meaning your analogy is rubbish. Are you calling yourself and engineer the way a plumber does? – matt Oct 12 at 11:33
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Your friend may also be referring to the tire being too wide for the wheel. In this case the normally flat surface is forced to curve in order for the side walls to fit into a narrower space.

As Paulster stated, there are a great many variables that come into play, but the basic idea is that a larger contact patch with the same tire compound and the same load and weather variables will have better lateral traction.

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As far as I understand the wider the tire is the more grip can be gained up to a certain point. That being, the vehicle"s weight is static and does not change but a wider tire will have a higher load rating (usually made for a heavier vehicle) that the smaller tire.

This means when the vehicle has weight on the tire the tire will deflect and deform to the surface of the ground. The lower the load rating and the lower the tire pressure the more deflection and more contact patch, high load rating higher pressure the less deflection and less contact patch.

The vehicle can only put it's own weight on the tire. So in theory if a tire is too wide, you may lose grip because the vehicle cannot exert enough force on the tire to cause it to deflect.

Think of a tire as a cylinder rolling on a flat surface. If the cylinder(tire) is deflated or has downward force applied, it will flatten on the bottom and create a large contact with the surface below it. The opposite is true if inflated or have downward force decreased. Only the very edge will be in contact with the surface.

Other variables do apply, such as tire compound, tire heat/pressure and road surface/temperature.

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A wider tyre does NOT put a larger static footprint of rubber onto the ground. The only way that can happen is if a lower tyre pressure is ran at the same time allowing the tyre to deform to a greater spread onto the ground, or a greater mass (weight) is sitting on that tyre. The contact patch static footprint shape will change, with a wider tyre, the contact patch will be wider, but also exactly proportionally narrower. It's simple physics.

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    Huh? A wider tyre will put a wider, and therefore larger, contact patch on the ground. How can it be both wider and narrower? The length of the patch is dependant on tyre radius and pressure, the width is dependant on tyre width. Changing the width of the tyre will have no effect on the length of the contact patch, but will change the width. – Nick C Mar 22 '18 at 10:03
  • Yup - a wider tire is always more rubber down (assuming all else is identical) – Rory Alsop Mar 22 '18 at 14:06
  • @NickC I honestly don't understand why this answer has been down voted. It is a fact that increasing the width of a tyre does not necessarily increase the contact patch. – matt Oct 11 at 16:42
  • @RoryAlsop your statement is demonstrably false ("wider tyre is always more rubber down"). There are numerous posts online with diagrams explaining why. You guys should remove your down votes for this post :( – matt Oct 11 at 16:44
  • is a graphic answer by the tire manufacturer Continental: a wider tire has a wider but shorter contact patch area. qph.fs.quoracdn.net/main-qimg-d26f4d6ac8fc8a28664441b573335761. NB. I got it from a quora post on the subject. Link is too long to share – matt Oct 11 at 16:48

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