[chrisguyw]

  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. I would not be surprised if some of the quicker Bordo racers will be using it.........

When the "air" wheels were first introduced, it was a fairly common practice to glue the tires around the inside and outside of the bead of the wheel, and use a syringe to pump a bit of air between the 2 inner flanges to remove the concave section of the tire. This "flattened" the running surface, which  provided a couple of very good benefits. 1/ It required less tire material to be removed in order to get a nice round and true tire, and, this "thicker" tread depth resulted in a tire with more compression which aided grip. 2/ The pumped in air also helped in providing more compression to the tire......when a tire can compress a touch, it will more effectively load the outside rear tire in a corner more progressively, adding more, and more consistent, grip.

The tires did tend to lose pressure fairly quickly and needed to be topped up between races/heats, and the sight of syringes on the top of everyones slot box, did not sit at all well with most of the owners of "family" slot shops..........so..........most (if not all) tracks banned the use of syringes several years ago.

So.....a different solution was needed,........ lots of folks are now using the process outlined below

Sponge tire blanks (doughnuts) are cut into strips, and glued (rubber/contact glue) to the gap between the inner wheel flanges.
They are then put into a tire truer, and taken down to size ( a few thou. proud of the adjacent flanges).

This provides all of the benefits of "air injection", and, is permanent..........more importantly, it does not offend the parents/kiddies in the shop   

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

Cheers
Chris Walker

Top...........A sponge tire (this is a Scaleauto Doughnut) and a typical "air" hub

Middle.......Sponge tire cut into strips, and glued to hub (use only contact cement or other flexible glue so as to not harden the sponge)

Bottom.......Trued so the the sponge is just proud of the flanges.........I regularly take the flanges down a few thou. to gain even more compression in the tire.