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Author Topic: Tyre treads  (Read 5149 times)

Offline P K Pillai

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Tyre treads
« on: 28/06/2013 16:33:40 »
The deep treads on a tyre decrease the contact area on a hard surface.How then does it increase grip? A bald, treadless tyre,with greater area of contact,should offer a better grip...?


 

Offline alancalverd

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Re: Tyre treads
« Reply #1 on: 28/06/2013 19:37:04 »
Depends on the road surface conditions. Some racing tyres ("slicks") have a flat contact area and are made from soft, almost sticky rubber: they give excellent traction on a dry drag strip but they are impractical for ordinary road use. The problem with road tyres is to get adequate adhesion in wet conditions and prevent aquaplaning. Lateral grooves act as pumps to remove water, but excessive lateral grooving, as on "town and country", winter grip, or tractor tyres, reduces lateral sliding friction and thus impairs cornering performance in dry conditions, so the dominant groove on a high speed road tyre is circumferential.
 

Offline syhprum

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Re: Tyre treads
« Reply #2 on: 28/06/2013 20:51:46 »
Tyres for road vehicles are essentially comprise  between road holding, in dry and wet ,life, and road noise as pointed out smooth tyres on a smooth dry surface produce the best road holding and shortest lap times on race cars but are hopeless as soon as the surface becomes wet.
The best compromise for road cars is a shallow tyre that has some ribbing to remove water and maintains the maximum area in contact with the road but unfortunately this by no mean produces the quietest or most comfortable ride and a car equipped with such tyres may well be slower on a less that smooth road than one with softer tyres over a long run due to fatigue produced by the harsher running.
I speak for experience having down many runs to Glasgow with a BMW E36 (deep soft tyres ) and a BMW E46 (shallow hard tyres).
« Last Edit: 28/06/2013 20:58:10 by syhprum »
 

Offline P K Pillai

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Re: Tyre treads
« Reply #3 on: 29/06/2013 01:59:36 »
Thank you.
 

Offline CliffordK

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Re: Tyre treads
« Reply #4 on: 29/06/2013 06:47:29 »
So, since we've likely had our last rain of the winter/Spring season....
Should I get a set of racing slicks to put on my car for the months of July, August, and September?

Then put my all-season tires back on mid-September?

Can I get a set that lasts better than the Indy tires?  I'd hate to have to buy a new set of tires every 70 miles or so.
 

Offline SeanB

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Re: Tyre treads
« Reply #5 on: 29/06/2013 07:24:46 »
Only if you drive on smooth roads with no spilled diesel fuel on them. Of course I see many cars here with "AirPlane" tyres, air inside, plain outside. Often on high end cars driven by people who think the service plan covers everything, and who are totally clueless as to the condition of tyres, the lack of lights on the car and who drive with the fog lights on at all times. A Range Rover which I saw parked at a high end shopping mall, where you could count the plies on the tyres, and the best one still had the remains of the steel belt on it, the rest were missing that, running on the canvas inner layers. Saw the soccer mom come back and place the 4 kids in the back, get in and drive off with 2 speed settings, on and off.
 

Offline CliffordK

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Re: Tyre treads
« Reply #6 on: 29/06/2013 19:50:06 »
Only if you drive on smooth roads with no spilled diesel fuel on them.

How much diesel (or water for that matter) would be enough to make a significant difference between smooth and course tread? 

Obviously in a downpour, one can get a significant amount of water on the road.  But, with a light mist, it may be just enough to get the road surface damp.  Would "channeling" the water still make sense?
 

Offline alancalverd

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Re: Tyre treads
« Reply #7 on: 29/06/2013 21:03:01 »
A hint of grease or water is enough to prevent slicks adhering properly - the difference between a lubricated and a nonlubricated condom! Lateral sipes allow the tyre to deform around the granular structure of the road surface and substantially increase torque transmission if the road is damp or greasy.

Aircraft tyres have minimal or no lateral grooves, so approximate to road slicks in one direction:

Quote
Viscous aquaplaning is due to the viscous properties of water. A thin film of fluid no more than 0.025 mm in depth is all that is needed. The tire cannot penetrate the fluid and the tire rolls on top of the film.....Dynamic aquaplaning is a relatively high-speed phenomenon that occurs when there is a film of water on the runway that is at least 1/10 inch (2.5 mm) deep.
 

Offline shagydeep

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Re: Tyre treads
« Reply #8 on: 02/07/2013 12:07:57 »
Hello,
On the hard surface you need bald Tyre.,..
 

Offline alancalverd

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Re: Tyre treads
« Reply #9 on: 02/07/2013 12:58:53 »
And you can see what happens to slicks by looking at the British Grand Prix! Dry, hard, smooth road, and general disintegration.
 

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Re: Tyre treads
« Reply #9 on: 02/07/2013 12:58:53 »

 

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