[chrisguyw]

So if air rims are such a problem ,and have to be filled in ,why use them ??

Steve

Hi Steve, They are not a problem., and with a bit of work, they can be excellent !!..............likely a little history will help.........When they were first introduced, the initial theory was that the unsupported middle of the tire  would expand at high speed (on the straights) giving a bit more top end, and then settle on the corners to provide more tyre surface area on the track. More importantly, "softening" the tyre by eliminating the solid center flange does help with handling/grip............the typical tyres run on most 1/32 cars are quite hard in comparison to sponge tyres, and the tiny thickness of tyre that covers the center rib of most 1/32 plastic car wheels results in a very hard tyre, and,  coupled with the relatively light weight of the cars, does not allow for much tyre compression at all.

Unfortunately, the unsupported center of the tyre resulted in inconsistent handling due to too much movement in the tyre. Soon after, most of the quicker club guys/gals, began gluing  the tyres around the complete circumference of both the inside and outside bead of the tyre and used a syringe to fill the gap with air. This provided a consistent handling tyre, and one that due to the air inside, compressed progressively, which improved grip/handling. While the tyres would lose pressure, and needed to be "filled" after a heat or so, the main issue that most of the clubs/commercial tracks had was syringes lying on everyone slot box, which was hardly the image most tracks wanted to promote, and the practice was largely banned.

In order to replicate the "air" affect without the air, many top racers looked for an alternative.........the sponge insert offers the closest performance to "air" without the negative imagery.

So, while they are a bit of work to retrieve maximum results, they are certainly worth the effort, arguably not so much for the home racer, but for top line competition, definitely.

There are a few folks now making double flanged wheels, with a flange on the extreme outside and inside of the wheels (similar to the 60's/70's designs), which have no center rib at all. These require a different shape tire (again similar to what was run in the 60's/70's) and for a given outside diameter, these tire have considerably more compression capabilities.

Cheers
Chris Walker