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Old 07-08-2006, 01:19 PM   #21
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Can I have a silver star cus I was nearly there?
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Old 07-08-2006, 01:20 PM   #22
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Sorry, second place is the 1st loser.
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Old 07-08-2006, 01:21 PM   #23
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Oh and sorry for calling you a nobba and trying to get you to go out and crash your car!!!
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Old 07-08-2006, 01:22 PM   #24
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Sorry, second place is the 1st loser.
1st loser's usually get silver stars though god damit!!!
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Old 07-08-2006, 01:22 PM   #25
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You and burty are the boatmad stunt car team.
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Old 07-08-2006, 01:25 PM   #26
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If your that confident in your/mr rockets theory lend us your motor and we'll try out Blufin experiment!!!
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Old 07-08-2006, 01:34 PM   #27
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I'm confident enough I understand the theory that I don't need to test it. If you doubt the theory, you're most welcome to test it yourself.
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Old 07-08-2006, 01:46 PM   #28
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ok, keys!!!
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Old 07-08-2006, 01:51 PM   #29
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In your own car, nobstick!

(Personally, I favour Nankang tyres pumped up as rock hard as possible)
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Old 07-08-2006, 02:06 PM   #30
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Re: Re: Tyre Width

Quote:
Originally posted by Johnny Rocket
They may do, or they may not, depending of the softness of the rubber and the tread pattern. Given the same surface and the same tyre compound and tread pattern, grip is not dependent on tyre width.
And does your space saver tyre have the same compound and tread pattern as the road tyre? And even if it does have a similar pattern is the block size reduced to fit the pattern onto the casing? Since the blocks squiggle, squerm and trip up and the narrow tyre is bound to roll over and distort the tread pattern when cornering, unless the rubber is seriously soft, it's likely to be a no. Unless it's raining, then it could be a yes.
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Old 07-08-2006, 02:42 PM   #31
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Matt's, Road Test with Space Saver fitted
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Old 07-08-2006, 02:46 PM   #32
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That's a secret spy shot of the ultima with its new engine.
Had to make a few bodywork changes to get it to fit.
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Old 07-08-2006, 03:55 PM   #33
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Re: Re: Tyre Width

Quote:
Originally posted by Johnny Rocket
It's counter intuitive, but that's the way the physics works.

The amount of grip is related to both the surface area of the contact patch, and the pressure of the tyre on the road. Pressure is "weight divided by contact area", so decreasing the size of the contact patch increases the pressure keeping the grip constant.
Hate to disagree, but......

The theory is that a very thin pont, with a mass of 'x' will exert a pressure on the surface, and will offer more resistance to movement than the same mass distributed over say '10x' An example of this would be to place a brick on a nail, then try pull the brick along the desk. Then place the same brick on a 2 foot square bit of hardboard, and try pull that along the desk. It is easier to pull the brick with the large surface area, proving that the smaller diameter ( the nail ) would offer more resistance to change, and would be better to hold an object like a car on the road in a corner.

This is true in a static example. If you had bicycle tyres on a car, pushing the car sideways would require more effort than if you had massivly wide tyres distributing the load. But this only works in a static example. It is clear that tyre width does affect cornering ability with the same compound of tyre. ( before someones cites the case that the average in my two examples would be identical - The same theory was applied to swiming in water vs swiming in syrup. "The added drag in the syrup should be offset by the increased power per stroke generated due to the increased dencity." The same thoughts may have been applied to the wider tyres vs thinner tyres.. 250kg per 1cm pressure for the thin tyres vs 25kg per 1cm for the thick tyres, but 10 of those cm on each tyre therefore the same total pressure should be the same. BUT experimenally the swimming in syrup vs swimming in water is the same theory has been proved to be false, and swiming in syrup is much slower. The same thing is proven by experimentation. We ran 185 tyres and has slower lap times. We ran 195 tyres and had faster lap times despite having more drag on the wider tyres....

Bringing this back to boats.....

There is a theory that states that the benefit of the added boyancy of seawater to a boats speed is offset by the reduced grip of the propellor in the water, so that a boat should go the same speed in fresh or saline water, the gains being offset by the disadvantages...

But I recon that like the swiming in water vs swiming in syrup, the actual theory "that's the way the physics works" isnt. Or perhaps there is more to the physics than meets the initial calculations.

Definately though, in snow or loose gravel I would prefer thin tyres to cut through the crap to get to the grippy stuff. But on tarmac ( dry ) the bigger footprint the better.
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Old 07-08-2006, 04:04 PM   #34
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Nope. Because the different materials in your nail vs harboard scenario give a different frictional coefficient (equivalent to a different compound). The nail example will also be applying sufficient pressure that it'll be deforming the "road" surface moving out of the normal zone of operation.

Try a small piece of hardboard vs a large piece of hardboard, both weighing the same.

jw, according to my sources, space saver spares are made from very soft compound, so while their area is low, the grip coefficient is quite high. This is done at the compromise of longevity. They also have a much higher ground pressure, so are less prone to aquaplaning in the wet.
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Old 07-08-2006, 05:55 PM   #35
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Quote:
Originally posted by Matt
Very good Mr Rocket. 10/10, and you can have a gold star.
Don't ye just hate a smart ass, teachers pet........I like being at the bottom of the class..........sorry...what's a wheel?????
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Old 07-08-2006, 06:07 PM   #36
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No wander they call this forum torkin bollix
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Old 07-08-2006, 07:19 PM   #37
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Quote:
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Sorry, second place is the 1st loser.

change the record!
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Old 09-08-2006, 12:31 AM   #38
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Here you go!

Quote:
Originally posted by Smith
you could probably work out the answer to that by carefully analysing a selection of skid marks
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Old 09-08-2006, 09:57 PM   #39
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Don't forget that your cornering will be limited to 1G however big your tyres, unless your car has a net downforce (both ends) at the speed the corner is being taken at.

Very few road cars have downforce at both ends at public road speeds.

Probably...
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Old 10-08-2006, 05:51 PM   #40
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The Escort Cossie was the first mainstream factory road car to have downforce at both ends apparently. I now await lots of pre Escort Cossie examples.
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