[Slalom4me]

  The problem with fitting standard urethane tyres to wheels with no solid centre ridge is that the tyres dish so grip is compromised. The standard wheels with urethanes were showing a definite dip in the centre.

Hi Gordon, there is a fix, and, it does add to the cars' performance.

Sponge tire blanks (doughnuts) are cut into strips, and glued (rubber/contact glue) to the gap between the inner wheel flanges.

This provides all of the benefits of "air injection", and, is permanent.

I (and many) have been using this process for several years, and would not think of reverting to a solid ribbed hub.

Although late to the table, I would like to join this conversation about the so-called "Air System" wheel design.

My exposure to Air System (AS) came through acquisition of 1/32 NSR cars (upon my return to the SR fold following a 45+ yr absence.)  I have an unassembled Thunderslot Lola White Kit which at a glance shares the same wheels as the NSR cars.

Ignoring marketing claims, I thought AS was primarily a logical development along the path of reducing inertial mass of the drivetrain - adding lightness, as Mr Chapman might have said.  Secondarily, it seemed that AS might facilitate tire growth as wheel RPM increased, as with the slicks on Top Fuel and Funny Cars - leading to a greater vMax than that of car not equipped w/ AS wheels.

My NSR cars are both fitted w/ stk NSR King EVO3 21.4K 360g.cm motors and one is driving somewhat lower-than-stk numerical gearing.  The cars run NSR rubber(?) and Paul Gage urethane tires on a large wood club track where tire treatment & glue is forbidden.  It is heresy, but these tires are not glued and not trued.

With all that said:

1)  It is interesting to read about Mr Steadman`s recurring issue with tire loss.  I haven't used witness marks to detect whether and how much the tires move on the rims, but a tire has never been thrown. 

2)  chrisguyw:  Can you help me understand how an Air System wheel that has its gap filled with a foam insert is anything but marginally (infinitesimally?) superior to a non-AS wheel with no gap? 

• The filled gap would facilitate a flat tire circumference at rest, like the non-gap wheel. So both should feature equivalent corner grip.
  
• The foam insert would be somewhat lighter than the aluminum situated in the same region of the non-gap wheel. So for an AS wheel, it seems possible that centrifugal force acting on the foam and the unglued center section of the tire MIGHT contribute to tire growth and greater vMax - tire growth that would not occur to a tire glued to the rib of a non-gap wheel.
  
• Cost and time to mount & true tires on filled AS wheels would be greater than on non-gap wheels due to the materials and labor to put sponge in the gap of the AS wheel.
  

No doubt it works, or you wouldn't be going to the trouble.  I just wish to understand how far along the scale of Diminishing Returns we're talking about here.

Regards