Are closed cell foam tire inserts waterproof?

[Gula]

Like these:

Crawler Innovations Deuce's Wild "Heavy Weight" 2.2" Closed Cell Foam (2) | eBay

The Heavy Weight product line is for heavy rc crawlers and speed applications. They do not fold over under load whether it's high speed, heavy weight, or simply turning. These foams rely on a small air gap between the foam and tire.

www.ebay.com

Or would water destroy the foam?

 

[89Industries]

They do not absorb water. Pretty sure they can sit in water without issue.

 

[smog]

I have run those Closed cell CI foams in a few rigs that regularly get Wet. Years later the foams are still like new