I've been noticing this since last Season.
Some Cars have a different rear Wheels than others (see picture). They are mainly used on fast Circuits.
Does anybody know what these are for? Aerodynamic? Brake Cooling?

It seems to be a combination of aero (reduced turbulence around the wheel itself), and cooling, as the reduced turbulence might ensure a better air flow as required by the brakes. This year I think Ferrari, Renault and Toyota use them, and did so at both Sepang and Melbourne, so I suspect it's more than just an aero device.

I haven't seen those too well, but there is no similar function in them as there is wheels they use in tarmac rallies, where wheel acts as air pump, pumping air from around brakes to out from those fins/passages wheel has?

Could it be that rear brake temps are too low without those? It looks like there would be less cooling for brakes but how it would be possible to know from bad pics

Is that white stripe in tires soft or hard compound?

Quote from JTbo :

Is that white stripe in tires soft or hard compound?

Soft. But you don't watch wingracing.

Quote from Blackout :

Soft. But you don't watch wingracing.

No I don't, however it is nice to know when I see pics, thx

Ferrari started them last year, around the same time the Renault's nose ballast was banned if I recall. They're stated purpose is better brake cooling, which work as tristan described.

I have a few guesses for this,

They may hold the rims surface heat higher (from brake heat) keeping tyre pressures more stable (heat from the rim increasing air temperature inside, would reduce the focus on only heating the tyre surface to raise the air temperature / pressure inside).

Also could help hold the brakes temperatures at a suitable level so they don't cool down too much on long straights.

I'd imagine there is also an effect on aero not dragging air at the back of the rims dished section.

I'm still unsure as to why the FIA hasn't banned these. According to the rules, wheels are supposed to be entirely made from one piece of metallic material, with nothing else attached.

Quote from spookthehamster :

I'm still unsure as to why the FIA hasn't banned these. According to the rules, wheels are supposed to be entirely made from one piece of metallic material, with nothing else attached.

It was all explained last year

http://www.formula1.com/insigh ... is/race/2006/754/267.html
http://www.formula1.com/insigh ... is/race/2006/755/273.html
http://www.formula1.com/insigh ... is/race/2006/763/321.html
http://www.formula1.com/insigh ... is/race/2006/764/327.html

Cool pic, turbulence i thnk