Physics talk

[bogan]

Increased pressure pushes the side wall out as well. So no dice on that increasing the circumerence.

Yup, it'll push everything out, so what was a squarish section gets rounded, allowing the center part to push away, increasing the circumference. Then again, this video shows drag tyres are just fucking crazy, look at the size of the rim locks on those fuckers!

[ducatilover]

My description earlier as to why the center of the tyre grows, happens as the RPM of the tyre increases. The burnout is used to make the tyre surface sticky, they just start the tyre low on pressure, because the increase is a side effect.

Yeah, posts seem to have appeared without warning.

Well, fuck me, playing with them and being well wrong I'd been told it was heat that makes the tyre expand. But, if it's just purely down to tyre speed, it could also make sense


These things happen when you live where I do though, sheep on the mind.

[Drew]

Yup, it'll push everything out, so what was a squarish section gets rounded, allowing the center part to push away, increasing the circumference. Then again, this video shows drag tyres are just fucking crazy, look at the size of the rim locks on those fuckers!

Drag tyres are made to do weird shit alright.

You're right with the circumference thing on a car tyre, I was only thinking about bike tyres when I said it.

[bogan]

This one is also very interesting...

[Dave-]

edit: I just had a thought, what's going on in this video isn't exactly as I've described, what I've described is wiped out by the bob and sway of the car going over bumps and braking etc, but the bumps and braking etc gives a good impression of what I'm describing, you can see that as he goes over a bump and the force pushing down on the axle increases the base of the tyre deforms more and more.

now while that's only happening to the bottom of the tyre, the rest of the tyre is expanding sure, but you'll find the gearing is based on the average (halfway), as it turns out from the mech student, the tyre gets more smaller due to this deformation than it gets larger due to tangential force, therefore at speed the tyres gearing goes down. and the speedo should reflect this.

But because they don't use an active filter on modern digital speedos you wont see this cause it's lost in the signal noise.

I feel we've achieved something here today. Back to network protocol design!

How the fuck did this get so convoluted?

To be honest I'm not even sure what we're arguing about now.

The contact patch expands, which lowers the radius of the tyre as I stated, as I also stated though it's blown away by the other factors, which I did actually make mention of, but to see the subtly of it you have to strip back all the other factors.

Are we in agreement?

[scumdog]

Fuck, even I did.


So, I haven't remembered everything in this, but has anybody actually given the correct anwser as to why the drag tyes grow so much? I don't recall seeing it and it's not centripetal force.

It's 'cos of the 'flingy-out-because-of-surface-velocity' fenomina, easy to explain eh!
Don't ask me to explain 'running-over-your-own-tread' fenomina though, it's a little trickier..

[ducatilover]

It's 'cos of the 'flingy-out-because-of-surface-velocity' fenomina, easy to explain eh!
Don't ask me to explain 'running-over-your-own-tread' fenomina though, it's a little trickier..

Could you please explain it in such eloquent terms (you said not to, I had to ask)
I want to quote it as verbatim next time I'm knocking some physics major tart off.

[mossy1200]

Funny shit happens after 88mph.

Tires get a bit taller and thinner because the weight wants to be further out . The fact there is a gas in the tire that doesnt mind the change in tire shape is the reason its able to do so.

[bogan]

as I also stated though it's blown away by the other factors, which I did actually make mention of

Funny, we must have all missed those parts?

"It is discovered that the increases of internal damping and speed will barely cause tire-road contact length to change."

we're talking 2.5 degrees either side of vertical, up to ~180kph

fascinating read, pity none of you can see it.

Zeng-Xin Yu, Hui-Feng Tan, Xing-Wen Du & Li Sun (2001): A Simple Analysis Method for Contact Deformation of Rolling Tire, Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility, 36:6, 435-443

http://www.tandfonline.com/doi/abs/1....36.6.435.3543

So, as the contact patch increases, the minimum radius must decrease, this is basic trigonometry.

It's ok chaps, no hard feelings, we use science to be right, not prove we're right.

Hmmm, missed them again it seems...

[bogan]

Funny shit happens after 88mph.

And if you ride with doug, funny shit happens well before then too

[Dave-]

Funny, we must have all missed those parts?



Hmmm, missed them again it seems...

Yes bogan, but here all I was doing is providing a citation, I would have assumed you'd read the whole thread ok? I'm sorry I forgot to mention it the 2nd time.

Also sorry for being a dick.

I've just done 14 hours a day for 8 days straight.

The something does decrease the radius of the tyre, but this gets wiped out by god knows what other forces are flying around and fucking shit up, which is why guys like drew are so amazing cause they know the sum of the fuck ups.

Are we all in agreement on tyre deformation now?

Funny shit happens after 88mph.

Tires get a bit taller and thinner because the weight wants to be further out . The fact there is a gas in the tire that doesnt mind the change in tire shape is the reason its able to do so.

funny shit actually happens near the speed of light, not even kidding.

Who wants to know what happens when you turn your headlights on at the speed of light?

[ducatilover]

Funny shit happens after 88mph.

Legit enough for me, three movies made about it. How many movies made about certifudge petals force?

And if you ride with doug, funny shit happens well before then too

You don't want to see what happens when I hit 100mph (a fence happens)

[mossy1200]

funny shit actually happens near the speed of light, not even kidding.

Who wants to know what happens when you turn your headlights on at the speed of light?

Thats silly. If your riding that fast headlights are a waste of time. Theres no way you could stop even if you did see a hazard.

[ducatilover]

Who wants to know what happens when you turn your headlights on at the speed of light?

Are you on a private road? You fucking hooligan

My theory, is your headlight turns on, but you don't see it (meh, closed road)

[Dave-]

Are you on a private road? You fucking hooligan

My theory, is your headlight turns on, but you don't see it (meh, closed road)

nah, photons do this cool thing where no matter what speed you're traveling at, they travel at the speed of light.

So if you're standing still and a photon goes past you, it does so at 200,000km/s

If you're walking along a road, and a photon goes past, it does so at 200,000km/s relative to you.

If you're driving in a car at 200km/h a photon will, to you, be going 200,000km/s

If you're traveling at 200,000km/s a photon will accelerate away from you at 200,000km/s

So if you turn your headlights on at the speed of light....they come on....duh? what did you expect would happen? lol