Does a tyre change its CIRCUMFERENCE when underinflated?

[Tim Streater]

For the purposes of this discussion, it is.

[Tim Streater]

... seem to think (sorry - ended that sentence early).

It can change *shape* but not *length* (except by 1% or so, which no one is disputing), and that is what I say above.

[Tim Streater]

You are.

And over a revolution, the rate must be the same, else the tread would come off.

[Andy Burns]

Now that we know that we're talking about detecting speed changes under

0.5% you can't discount a circumference change of 1%

[T i m]

So it can't change it's length but can change it's length?

Typical Brexiteer.

Cheers, T i m

[T i m]

Come up with the measurements then?

It's not mine, it's what those people who know know.

Ok. The belts are woven between the beads in a ziz-zag, working their way round the tyre till they join up again. these cross at roughly 90 degrees and form a parallelogram. When you load a tyre that causes it to widen, it has to get the material from somewhere and because the rubber is 'bound' to some degree by the bets, the only way that can happen is some foreshortening of the length of the tread from where it's distorted.

What do you have as an alternative explanation?

They are everything like that (but maybe you just don't realise it)?

You are Rod aren't you ... ;-(

Cheers, T i m

[T i m]

It's exactly for the purpose of this discussion IT ISN'T!!

Brexiteers eh ... ;-(

Cheers, T i m

[T i m]

Aww Bless. The poor goblin is so confused now ... glimmers of understanding but can't_actually_say_it for fear of upsetting his goblin master, the great Turnip. ;-)

Whoosh.

The rate of shrinkage of the tyre is fixed (it's not of course as the load on the tyre is dynamic in use but that would be a step way too far for the Streater goblin's tiny brain) for a good (non punctured) tyre but the location of the shrinkage moves round the tyre. The bit that is causing the tyre to shrink is the bit sat stationary on the road so no damage to the tyre occurs.

So, you can have an effective circumference that is smaller than the unloaded one that does not put the tread under any additional stress.

*That* is QED.

Cheers, T i m

[dennis]

So that you can prove something that actually wors doesn't and for you to win a false argument! Then you claim to be using physics. You must be a failed climate scientist who thinks proving the impossible by changing the laws of physics is a good thing.

[The Natural Philosopher]

And others have indeed done this, and there is a videos showing it tghat proves my point

But you dont need to do the experiment, correctly applied mecahanics gives the correct naswer.

[The Natural Philosopher]

Oh but they do.

now measure the distance between the axle and the road on te inflated and deflateted side and tell me oif they are 0.4% different or a far larger number.

[The Natural Philosopher]

Just shows that a 27 year old gorl is completely unable to have a basic comprehension of engineering anmd mechanical sciences just as much as her benighted stupid dad.

[dennis]

A flat will change by more than 0.5% as shown empirically by another poster.

Its also fairly obvious that it will from the destruction of one twin wheel tyre on a lorry. If it only changed by say 1% the tyre wouldn't generate enough heat to destroy it and its the heat that does it.

On single wheels the friction between the slower moving inner bit of the tyre and the outer will generate plenty of heat and wear to destroy the tyre.

The twin wheel one won't have this contact so the heat generated in compressing and stretching the tread is what does it.

[The Natural Philosopher]

We dont.

That sort of change is about what one would expect from steel or kevlar cables.

[The Natural Philosopher]

It is far more fixed than the distance of te axle from the road....

[Andy Burns]

what aspect of it?

who, where? I might have missed it ...

[Andy Burns]

we seem to have some people saying "it doesn't happen, but it does happen a bit"

others saying "it does happen but it's insignificant"

others saying "it happens and it's enough to be significant"

is there anyone left saying "it doesn't happen fullstop" ?

[dennis]

You are being obtuse to troll. The above says the rate varies around the tyre, the average is one rev of the tyre is one rev of the wheel. The distance covered will be the average. The average will change depending on the static load, the pressure and the dynamic load. The reason it changes is because the circumference changes when all these forces are acting on it.

Now snip that to try and prove I said something else but remember everyone else has already read it except for the idiots like TNP that have killfiled me because they can't argue with someone that is correct.

You shouldn't listen to TNP, he claims to understand engineering and physics but as you can see from this thread he is closed minded and will fight his position long after it has been shown to be wrong, just like you.

You, TNP, and harry have that in common. I guess thats why you still support brexit as you can't see the problems that it is producing and will keep you "solutions" in your mind no matter how wrong they are proven to be.

[T i m]

;-)

As I said, they will all get there in the end Andy ... they will have to because:

1) It's obviously *the* answer

2) They don't have any alternative explanation

3) They will (therefore) have to to stand any chance of retaining any credibility (even they get some stuff right sometimes). ;-)

Cheers, T i m

[T i m]

Sounds par for the course.

The actual names for it are 'guesswork' and 'hunches'. Same rules as the used for Brexit of course.

No, he's a failed Media Studies student who had to then do Fine Arts. ;-)

What he isn't is an Engineer, that's for sure as some of the stuff he's be coming out with are soooo bizarre easily demonstrate.

Cheers, T i m