Tyres - Page 2

jomor · 29-04-2003

Guys, its physics, bigger surface means nothing to grip. It depends only on tyre and road surface quality and the car's weight. Period. No matter what you believe or have experienced, you cant change or invent new physics laws

Wider tyres have different structure and give better steering accuracy, bending less and passing all road details to the driver (having lower profile). If the rubber material is the same, you get the same grip, if any tyre salesman told you different, he fooled you, sorry.

And one more thing, you DONT get nessecarily bigger surface with wider tyres, in fact the touching area widens, but its lenght gets a bit shorter, thats because smaller profile tyres bend less. But even if you did get more surface, it doesnt matter to the friction force, sorry.

RicksAlfas · 29-04-2003

<blockquote>quote:<hr />Originally posted by jomor:
Guys, its physics, bigger surface means nothing to grip. <hr /></blockquote>Please explain why dragsters and F1 cars have the widest tyres going??
Surely the wider the tyre, the more surface area is in contact with the road, so there is more grip.
Slick tyres have the most grip because they have more rubber in contact with the ground.
We are not talking about cornering or handling dynamics, just straight forward grip. When it is wet or snowy, thinner tyres are less prone to aquaplaning because there is less surface area.

Mel Bonkers · 29-04-2003

Ricks,

I think jomor is right somehow. If you look at the surface of contact of F1 tyres, that is pretty much VERY SMALL (the size of your hand). The fact that the slicks give more grip is due to rubber compound. If I'm correct, in a straight line, the new slicks with grooves are faster than the old slicks, because you simply have LESS FRICTION because there is a smaller area of contact. However, due to the downforce the car can maintain very high speeds in corners without loosing grip. If you take of the wings, the cars can't reach that same amount of speed, although the tyres remain the same. However.....I'm not sure

I think the big tyres with dragsters are used, because otherwise ALL RUBBER would've been used during the start and they wouldn't get far laughing

RicksAlfas · 29-04-2003

Maybe

I just see it has the more rubber in contact with the ground at any one time, the more grip there is.
In fact forget the rubber - it would be the same with wooden wheels, or stone wheels.
If you have an old grinding wheel in your windmill, you would grind more grain in a day if your wheel was bigger than a small one, 'cos more wheel would be in contact with the stone.
http://www.hogacompany.com/mill11.gif

Mel Bonkers · 29-04-2003

My God Ricks, first baby-chassis-folding-in-Sportwagon, now mill grinding.....you sure have strange hobbies laughing

RicksAlfas · 29-04-2003

<blockquote>quote:<hr />Originally posted by Mel Bonkers:
My God Ricks, first baby-chassis-folding-in-Sportwagon, now mill grinding.....you sure have strange hobbies laughing <hr /></blockquote>I just nipped out and took that pic laughing

jomor · 29-04-2003

<blockquote>quote:<hr />Originally posted by RicksAlfas:
Please explain why dragsters and F1 cars have the widest tyres going??
Surely the wider the tyre, the more surface area is in contact with the road, so there is more grip.
Slick tyres have the most grip because they have more rubber in contact with the ground.
We are not talking about cornering or handling dynamics, just straight forward grip. When it is wet or snowy, thinner tyres are less prone to aquaplaning because there is less surface area.<hr /></blockquote>I dont wanna offend anyone or be a smart-arse here but you just need to undust the school physics books.

Friction force is given from the following formula:

T = n*Fk

where T = friction, n = coefficient of friction, Fk is the vertical to the surfaces force (in our case the car's weight). The n coefficient depends only on the surfaces characteristics.

The fact that on drag races have huge tyres is based on temperature handling and not the grip. The fatter the tyre, the more it stays warm, it has to do with the temperature spread mechanism. And there is one reason, spinning, they cant have tiny tyres to spin, they need big amount of rubber so the tyre doesnt change geometry by excessive wear.

No matter what you believe or want to believe, size doesnt count on grip.

ajcarter · 29-04-2003

Also drag tyres expand when they spin faster, giving bigger radius.

As for the thinner tyres in snow - yes they do give more grip. Wider tyres compact the snow underneath them, and as we all know compacted snow is like ice. The reason thinner tyres are better is because they are so thin and round (the surface in contact with road) the snow gets pushed out the side of them.

Mel Bonkers · 29-04-2003

I found this article on the internet (seems jomor knows what he's talking about wink )

http://www.autospeed.com/cms/A_0996/article.html

jomor · 29-04-2003

thanx for the trust Mel

New signature recommendation: "Size doesnt count!"

RicksAlfas · 29-04-2003

Jomor
If Mel believes you, I believe you!
I never really got to grips with all that stuff about
xy2 / a% = radius of a grape

I will look forward to seeing the new Goodyear Eagle F1 J-0mor in 115/35/17" ZR rating
laughing

Mel Bonkers · 29-04-2003

<blockquote>quote:<hr />Originally posted by RicksAlfas:
Jomor
If Mel believes you, I believe you!
I never really got to grips with all that stuff about
xy2 / a% = radius of a grape<hr /></blockquote>laughing laughing laughing

I feel a signature change coming up!

jomor · 29-04-2003

<blockquote>quote:<hr />Originally posted by RicksAlfas:
Jomor

I will look forward to seeing the new Goodyear Eagle F1 J-0mor in 115/35/17" ZR rating
laughing <hr /></blockquote>Good idea! I have to make a living you know

Food, clothes, GTA and everything... wink

115/35... our Fiat 127 had 135/80/13

and just to clear things out, i love wide wheels wink

btw i was just looking the meeting's pics again and again.. that blue GTA is so damn gorgeous.. i ll never afford her

http://www.alfaowner.com/forum/ubb/icons/icon33.gif

Stori · 01-05-2003

<blockquote>quote:<hr />Originally posted by RicksAlfas:
 <blockquote>quote:<hr />Originally posted by Stori:
What are your complaints re: the PZero Nero's and what are you going to replace them with and why.<hr /></blockquote>Hi Stori
I have only had them about 6000 miles, but first impressions are that they are noisy, and don't grip particularly well. They certainly don't inspire confidence on wet roads, and wheelspin is a constant problem turning out of damp junctions. Main plus points are that they look good and are Italian. Wear rate is OK I suppose.
Next time round I think I will try Michelin Pilot Exaltos or Pilot Sports.
They are on 7 x 17" Alfa alloys on a 156 JTD SW V2 - 150 bhp, but it's the 305NM (225 lb ft) of torque that's defeating them!!
Cheers
Rick<hr /></blockquote>I believe that the PZero Nero's are quieter than P7000's.
I have the Pzero Nero's on my 147 TS 2.0 and they seem to be quite good and predictable. But I do not have your massive torque output frown

Reuven · 01-05-2003

I too have a set of P Zero Neros I am pretty happy with them, great on highway driving but I do find them a bit loud on an ash felt surface & some times they slip & slide in the wet if you corner to hard!

But you have to make sure your tire pressure is around the 36 psi mark then they should be ok.

But I may try P7000's next time to compare the difference.

Stori · 01-05-2003

I run my Alfa 147 Pzero Nero's at 40 psi front and 36 rear

Actually even if P7000 were better and I believe they are not, I do not think they are available any more in Australia

RicksAlfas · 01-05-2003

<blockquote>quote:<hr />Originally posted by Stori:
I run my Alfa 147 Pzero Nero's at 40 psi front and 36 rear <hr /></blockquote>Bloody hell Stori! No wonder your Avatar is a kangaroo! It must bounce all over the place.
laughing
As an example, my 145QV (2.0 Twin Spark) is 34 front, 31 back....
eek!