I must admit, I thought that the difference between open cell vs closed cell was simply whether the insert had a cut slit. Many of the HPI foams were just a flat piece of foam that I would have to patch together with some contact cement in order to "close" the foam up, hence why I thought that is what made their foams "open cell".

I found this link here which explains the difference between open and closed cell foams, and frankly it's nearly impossible to tell the difference to an untrained eye:

http://www.foam-tech.com/products/ur...losed_cell.htm


How is an entry level racer going to figure out what to select when manufacturers don't specify, for example these foams here are billed specifically for asphalt racing:

http://www.sweepracingusa.com/110-TC...et_p_207.html#



then these foams here are billed for carpet racing:

http://www.sweepracingusa.com/110-TC...set_p_412.html




Now I can't tell the difference whether it's open or closed cell (they don't say anywhere in the product details that I can see), but it would make more sense to me to use the appropriate foam for the intended application by the manufacturer to get the best possible wear and performance out of the tire. Both from an economical and performance point of view.

I've been running the first set of foams in my 24mm RIDE tires on an asphalt track for a few race days and my car has hooked up like it's on rails with nearly no signs of tire wear. Nothing close to what I was seeing with the HPI tires.

It will be interesting to test and see both in performance and wear with the new spec tire/foam combo and contrast them with what I've been using lately.