Traction.......the grip issue :)

[oddytomtom]

Originally posted by Skii
So if wider tyres don't give you more grip, why did F1 make them narrower a few years back?

to slow them down, and thats no joke, they hoped to slow then down and give them less grip so that the cars could overtake easier, didnt work tho lol

[Zak33]

Originally posted by Lowe
I'm very suprised. If it doesn't give more grip, why do I need to be the Hulk when driving around with 195s on compared to my old 135 bike tyres?

now THAT is a good question.....why does Lowes steering WEIGH so much now that he has 195's?

A: Because on a wide (195 in this case) tyre, the tyre blocks (raised areas of the tyres) grip on their EDGES as well as their road surface....and the tyre itself flexes to allow it...its why they are more tenascious in corners.....its why they work....the try harder at different angles

if your old 135's (more likely 155 or 165) had been as flexible and supple they would have been bloody hard work too....but they were not....they were more rigid, they flexed less....cos they were cheaper

how to explain better *scratches head*

OK....a cheap small narrow tyre is often very inflexible.....and the blocks of tread are hard.......go to QuikFit and stick your thumb nails into the tread on a cheapo tyre.....it'll hurt, cos it'll be like wood

get a cheap pencil rubber/eraser (the hard ones) and hold in down onto the desk with all your might.....narrow end down...and twist. Dead easy..no grip (what you expected)

Now.....get a good quality, soft malleable pencil rubber/eraser, lay it on its flattest side....and push down and twist.....its hard to move... (no suprise)

Now reverse the pencil rubbers/erasers and do the oppsotie job...

the soft one is STILL hard to turn even though its on its narrow end....as long as you put the same pressure on it.

and vice a versa....its a rough example BUT you have lots of those on your tyres.....so its a reasonable demonstration.

PLUS LOWE....your new wheels have a different offset with those tyres.....even a 2CV can be made to be impossible to steer , just with suspension tweaks.....its a geometry thing that I find hard to even understand, let alone explain....

The point being that your car is hard to steer because the tyres are BETTER, higher grip coefficient, and are in a different place in relation to the leverage point on the steering rack.....not cos they are just wider and therefore have more grip.

If we put old 195's on from the early 90's (Michelin X's) you'd be able to steer OK, but you'd die at the first roundabout

[Zak33]

Originally posted by oddytomtom
to slow them down, and thats no joke, they hoped to slow then down and give them less grip so that the cars could overtake easier, didnt work tho lol

PERFECT reply....for slightly the wrong reason

It WAS to slow them down, but not cos the WIDTH gave less grip.....but cos they wanted less power put through them if they were to last the distance and not wear out, or if the compunds were softer to deal with the power, they'd heat badly and blister......it kinda back fired cos the tyre boys were a step ahead and as you say..it didn't work....

BUT.....it was only described to the public as being to reduce grip cos it was easier to explain to Jo Public.

What we are all here trying to understand is that is was deeper reasoning than that......it's wear rates and heat build up , caused by narrower tyres.....and THEN you have less grip. But only after a period of time.

IN A SPRINT EVENT.... an F1 car could use narrower tyres than they already use......monster soft..........and skinny for aerodynamics.

[Zak33]

Originally posted by Deckard
Cos bigger wheels means a bigger top speed.

NOPE.....you can do that in the gear box....and I do mean Diameter...

why do we need bigger wheels?

[TiG]

To fit bigger break disks?, most cars seem to have much larger break disks, surely some of the discs fitted to cars need the larger wheel size to allow them to fit?.

Or is the bigger breaks just because they have more space whatever other reason they use bigger wheels ??

TiG

p.s no we haven't finished the 4 wheel drive debate. not until i've test driven both the vRS and the 4x4T

[Zak33]

TiG...thats it exactly....

Bigger brakes.......abd better cooling too

Right..........better tyres, not wider

[Lowe]

Beaten to it - net died so I couldn't reply.

I wanted 4 pot Brembos on the Clio with a 305mm disc. However they won't fit under 15" rims. Since I don't want to lose my rapid acceleration, I don't want big wheels.

Even more frustrating is that Brembo make some which would fit under 15s, but they're motorsport only.

[[GSV]Trig]

Originally posted by XTR
ever seen the rally car's in the ice/snow? look at the width of the tyres

They have thin tyres that cut thru the ice and sludge instead of slipping about on the surface crap...

[Zak33]

Originally posted by [GSV]Trig
They have thin tyres that cut thru the ice and sludge instead of slipping about on the surface crap...

True..but even on tarmac those cars dont have monster width tyres..yeah they are wider, but they aint HOOGE....

Suprised no one has mentioned DRAGSTERS.....
they have hooge wide rear tyres so Zak33 MUST be wrong there...mustn't he ?

[TiG]

can you say centrifugel (sp?) force, tires aren't big and fat for long. When you ram 1000?HP through em they soon become rather skiiny.

TiG

[Rave]

Originally posted by Zak33
True..but even on tarmac those cars dont have monster width tyres..yeah they are wider, but they aint HOOGE....

I did some work experience on the WRC scoobies for two weeks a few years ago. Back then I didn't really pay attention, but the road tyres were probably 245s on 18 inchers. The cut slicks looked amazing on gold Oz alloys, man I'd have killed for those . We put some road Pirellis on the car to take it to the product launch for the tyre (Pirelli were a sponsor)....mainly German journos for some reason . Anyway that's beside the point, I got a ride in the car with the road tyres on after the event, and the grip+ acceleration out of corners were ****ing unreal

The gravel tyres were pretty small and ordinary looking. Very light though

Surprised no one has mentioned DRAGSTERS.....
they have hooge wide rear tyres so Zak33 MUST be wrong there...mustn't he ?

Hehe, I know why that is. The sidewalls are extremely soft and flexible. At high speed the tyres deform and their outside radius increases, which in turn increases the car's gearing for a higher top speed. 0-300 in 5 seconds? That'll do nicely, thank you

Good thread this Zak, I must admit I didn't know that width made no difference, which I really should have done. I won't be so keen to get 15s on my MR2, I'm running Yokohamas on the front anyway.....

Rich :¬)

Edit: beaten to it. Tig, a top fuel dragster puts out about 5000BHP, top alcohol 2-3000.

[IainB]

Oops -
So is a soft compound and a VERY wide tyre bad for a drag car
Could have save myself loads of money - only joshing mate !



But then again, I could always use these, just not on the road !!



Damn interesting post again Zak - missed this one....

[RocketmanX]

Good one Zak !

Great subject

Nice intro

For those having trouble getting this maybe looking at it from another angle may help.

The wear thing Zak stated is true and what causes wear?
The weight and centrifugal force being applied to the tire, just as Zak said.
A car with stiff springs and a tire width of say 10" (standard racing width over here for us Circle "Jerkers") will have grip up until a fixed amount of side force overcomes the amount of weight being applied down (Static and transferred weight) on the tire. If you take the amount of weight being applied down on the tire and spread it across a greater width you get less weight per insch of rubber- hence the same amount of grip per corner. Weight transfer and the ability of the car to distribute the side loads properly are what produce a higher corner speed. More weight over any given wheel, if too much, can actually cause the tire to overcome it's ability to grip the road by adding too much to the amount of cintrifugal force to that corner. In other words, too stiff a spring can cause loss of grip by transferring too much weight to that corner thereby taking away grip from other corners. That's why they like to call it "balance" when they talk about how a cars handling. At least that's a favorite saying in NASCAR over here.

Ok, hope that helped. Forget what I've typed since I get to trying to keep my fingers up to speed with my head and always get behind

[wol]

Originally posted by Zak33
GO ON...GUESS.....why do competiton cars get designed around bigger wheels? Why is the wheel arch so big on an EvoVIII? And why is it so important, that even the gearing is designed to suit a car with mammoth wheels?

Suspension travel?



Wol

[blockers]

Now im confused. One F1 cars the tyres used to be completly slick yes? Not a groove in sight. making the car have better grip? Surely the tyres were wider, now they are thinner with grooves they have less surface area? Therefore more grip than the old slicks....

Im probably just lost somewhere 80miles East of you guys.....lol

Will

[Big RICHARD]

Originally posted by blockers
Now im confused. One F1 cars the tyres used to be completly slick yes? Not a groove in sight. making the car have better grip? Surely the tyres were wider, now they are thinner with grooves they have less surface area? Therefore more grip than the old slicks....

Im probably just lost somewhere 80miles East of you guys.....lol

Will

The reason for less surface area is not grip. It is because the less surface area you shove 1000bhp through, the more heat build up you get. Eventually (pretty quickly with low surface area!) your tyres give up and bubble and crust (when they overheat they go hard and 'burnt') THIS is your reduced tyre grip.

F1 tyres at working temperature (~100 deg. C) are VERY soft and 'squidgy' this is to improve their 'stickiness' (read: coefficient of friction) and therefore grip. When overheated this squidgyness (coefficient of friction) is reduced.