Tyres on the wrong way for over two years

[Racing roadkill]

So by having tyres on the wrong way round the fabric of space time is unravelling or have I misunderstood?

Yes you clearly need to re think your life.

 

[Racing roadkill]

Sorry... could you repeat that for me?

https://www.scientificamerican.com/article/how-do-dimples-in-golf-ba/

This is the same effect, but on golf balls.

 

[Racing roadkill]

I think he's saying that it has the same effect as the dimples on a golfball, the 'port' on my speakers is dimpled for a similar reason.

That’s not far off.

 

[Racing roadkill]

So at 20 mph a small part of your tyres is hitting the air at 40 mph? And they are trying to make them aerodynamic?

Pretty much. “Trying” being the operative word.

 

[Ajax Bay]

Barman! I'll have some of what this chap is drinking.

Pretty sure he has you on ignore (or he is exhibiting restraint the like of which we have not yet seen), and you're not the only one. Have a great 'Kintyre' Hogmanay.

“Trying” being the operative word.

Not even sure if they're "trying". Serendipity not design.
"the ‘tread’ is there to trap water as the tyre rotates" What speed, compared to the road surface, is the "trapped" water travelling at? Will H2O's Reynolds Number be approached?

 

[Ian H]

I read somewhere that the only reasons for tread patterns on road tyres were, a) brand recognition and, b) because many riders were instinctively reassured by it.

 

[winjim]

There is a purpose to having tyres with ‘tread’ on the shoulders ( it’s not tread, it’s not there to enhance grip, or move water ) with the arrow pointing in the correct direction. It’s there to make sure that the manufacturers ‘power’ spec is applicable. The Q.A. compliance people don’t like it if a tyre’s spec can’t be matched in the real world. The ‘tread’ is an aerodynamic / fluid dynamic device, to ensure any aero drag caused by the tyre is minimised. Air against air / water against water is less draggy than rubber against air, or rubber against water, so the ‘tread’ is there to trap air / water as the tyre rotates, which reduces drag, and gives the manufacturer something which helps them ‘prove’ their figures. With a slick tyre the arrow points so that the tyre rolls in the direction that the tread was laid onto the carcass. The boundary between the carcass and the tread is not actually perfectly uniformly flat, it’s ever so slightly ‘pear shaped’, in order to keep the tyres performance as ‘per spec’ the tyre should roll from the bulb to the tail, on each rotation ( this is also the case with ‘patterned / treaded tyres, but the pattern overrides the tread / carcass interface issue with patterned tyres) All of this is of little real world consequence, but compliance / Q.A. are a pain in the butt, and need stuff like this to keep them quiet.

I have questions. What is "'power' spec", how is it defined and how is it measured?

 

[Racing roadkill]

I have questions. What is "'power' spec", how is it defined and how is it measured?

It’s power loss difference compared to a standard. Measured in Watts. They run a tyre with an agreed size, shape, design and composition at a certain speed, in agreed standard conditions, for an agreed standard time. Then work out the power required to do so. Then run their comparison tyre in the same conditions and compare results. It’s not an industry standard test, there is no regulatory requirement to have the figures, so they can only state comparisons between tyres. There are tables of results, in cycling publications where tyres are tested for relative power loss. The tyre manufacturers often have their own internal specs as well.

 

[Justinslow]

Just read this whole thread.....

And we wonder why the powers that be can’t sort out Brexit.