Tyre widths

Steve

Steve

Steve

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Was reading an interesting discussion on this with the idea that tyre width isn't the be all and end all when it comes down to transaction, and that it is just a bigger must be better mentality.

The scientific reasoning is that the same pressure a 255mm and 225mm tyre will exert the same footprint on the floor, the 255 being wider but narrower and the 225 having a narrower but longer one.

The wider tyre gives poor aquaplaning in wet conditions so arguably a narrower tyre will always rule?

The only true way to gain traction is the grip facto of the rubber compound (I for get the term) and increasing rubber by reducing tread cuts like the toyo r888s

Side wall strength seems to be far more important for the most part

Now that makes sense and is something I had not thought of before.



I am sure there are some far more knowledgeable people on here than me who could chip in.
 
you are wrong, wider = better traction.

do you seriously think everybody including car manufacturers, tuning houses and race teams have been getting it wrong for all this time? :rolleyes:
 
Clarkey said:
you are wrong, wider = better traction.

do you seriously think everybody including car manufacturers, tuning houses and race teams have been getting it wrong for all this time? :rolleyes:
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exactly

Formula 1 teams spend hundreads of thousands of pounds researching tiny bits of carbon fibre in order to gain 0.01 seconds per lap due to improved aero performance.

Do you really think that after all that research, they'd never have discovered that the best traction doesnt come from the widest tyres possible ?
 
He's talking about footprint though, a tyre that's wider could quite possibly have less "length" in contact with the road if it doesn't flatten out so much. I suspect though that wider tyres are run at a slightly lower pressure though so that they have much the same length of the tyre in contact with the road.
 
Jokester said:
He's talking about footprint though, a tyre that's wider could quite possibly have less "length" in contact with the road if it doesn't flatten out so much. I suspect though that wider tyres are run at a slightly lower pressure though so that they have much the same length of the tyre in contact with the road.
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that would only apply if you changed the radius though.
 
so why dont car use bike tyres? :)

to be honest each chassis has a "sweet" spot on wheel/tyre sizes, go to far over/under this and it will make it worse.

Narrow tyres resist aquaplaning cos they cut through water better (same reason snow tyres are narrow). Also cos more pressure is on the road per CM/2.

Wider aquaplanes cos the path to the side walls is futher so the water cant escape fast enough. But if you have good rubber it shouldnt be a issue.

I think the point you are trying to make is the area on the ground vs the pressure on the ground. Bigger tyres = more surface area, but less pressure on that surface area so same grip? i doubt it works that way really?
 
lol sorry about the wider and narrower bit, wasn't making myself clear

a tyre with the same radius and pressure would have a static contact patch size even if it was say 225mm and 255mm in width

There is a whole physics explanation that eludes me.

Although i is so ingrained in us that wider is better when ever this topic comes out you get the roll eyes and don'r be stupid comments :P

I am just starting a debate oin this as I don't know all the ins and outs
 
I am not claiming anything as it is a new idea to me but makes sense :)

no because the fiat panda had different diameter wheels a tyre profile

This link shows how when changing tyre width on the same sized wheel at the same presure you are just changing several elements of the friction formula so the end result is the same.

Think about it to maintain the two different tyre sizes at the same pressure the wider tyre requires a greater volume of air as they are suporting the same weight of car, therefor the tyre deforms differently, the wider tyre squashes less but is wider to start with, the narrower tyre squashes more so although a smaller width, the overall foot print is the same.
 
Clarkey said:
you are wrong, wider = better traction.

do you seriously think everybody including car manufacturers, tuning houses and race teams have been getting it wrong for all this time? :rolleyes:
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He is not wrong, he is correct if the tyre is of the same rolling radius as before. An example would be my car, I went from a 205/55/16 to a 255/40/17. For sake of arguement they are an exact match, then the foot print of the tyre is pretty much the same size.

On different cars then yes it does make a difference, as you intimate you wouldnt stick a skinny set of wheels and tyres on a supercar.
 
Amazing, I'd better phone up Bugatti right away and inform them that the 365 section rear tyres on the Veyron are too wide, would be better on some 225's.
 
[TW]Fox;11942320 said:
I dont understand how something can be wider AND narrower?
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He is talking about footprint. In my example in the previous post I went from a 205/55/16 to a 255/40/17. There is a slight difference but just for the sake or arguement they were exactly the same, what he is saying is that the original footprint went from a long and narrow footprint to a short and wide footprint.

On the original narrower tyre, when you accelerate the larger aspect ratio causes the tyre so squash down a bit when the car squats, therefore you get a longer contact patch and perhaps a very slight increase in width. On the wider tyre, the smaller aspect ratio would mean there is a lot less tyre squash when the car accelerates and squats so you get a shorter contact patch but you have greater width.

What this means is that on a straight line launch, I would expect the skinny tyres to perform better than wide tyres (longer contact patch) but on cornering the wider tyres would perform better (wider contact patch).
 
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Clarkey said:
Amazing, I'd better phone up Bugatti right away and inform them that the 365 section rear tyres on the Veyron are too wide, would be better on some 225's.
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Now you're being stupid. As I said, it only works if you change the tyres and wheels on the same car IF you keep the same rolling radius, tyre pressure.
 
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Clarkey said:
Amazing, I'd better phone up Bugatti right away and inform them that the 365 section rear tyres on the Veyron are too wide, would be better on some 225's.
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Show me some maths or give me a reason that you disagree with the hypothesis?

For side g in corners then ther is more benefit I believe as the ratio between side wall and width gives less flex so helps grip.

If width was everything then cars would be rucking about on 1000mm tyres.

Car weight will play a massive part in the tyre width choice.

I am not a tyre engineer nor do I have fantastic knowledge in physics but It makes sense and I can't propose a reason against it, so until someone can then I Will sign up to it being correct
 
Steve said:
Show me some maths or give me a reason that you disagree with the hypothesis?

For side g in corners then ther is more benefit I believe as the ratio between side wall and width gives less flex so helps grip.

If width was everything then cars would be rucking about on 1000mm tyres.

Car weight will play a massive part in the tyre width choice.
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The theory doesnt work on different cars only the same car, using different sized wheels and tyres ( diameter and width) whilst keeping the rolling radius and tyre pressures the same.

If you take a car, when you change the size of the wheel to a larger wheel for instance from say 15inch 200wide to 18inch 255wide you have to change the aspect ratio of the 18inch tyre so that you keep the same speedo reading. Therefore the diameter of the overall tyre is exactly the same.

If you have the same tyre pressure, the weight of the car is the same, then the only difference is the shape of the contact patch, which as you say is pretty much the same size therefore in real terms you dont get any more grip only the performance of the grip in certain situations.

The idea doesnt hold true across different cars, as everyone has said super car tyres dont perform the same as Panda car tyres given the same tyre and compound.
 
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