The first test of this at Silverstone has come and gone and I missed the news articles about it from a week or so ago.
https://us.motorsport.com/f1/news/wh...plex/10498480/
In short, the first test wasn't particularly successful. It did reduce some of the tire spray, but they are seeing that the bulk of the spray is being kicked up by the diffuser (no surprise here) and not the tires. That at least for this first test, it really didn't have a substantial impact.
They are looking to do more testing (which is probably right thing to do), but it is not looking good for a purely tire based spray solution. I can imagine when it's all done, the answer will be the only way to really prevent the spray would be significant and likely unacceptable aero changes.
Richard