I went in to hobby shop to buy Bullfrog Snot and was blown away by the $25 plus tax price for a small jar! That's way too expensive for traction tires, so like Dennis does, I will use the silicone.
I've wondered if "Bullfrog Snot" is maybe similar to "anti-squeal compound" used on the back side of automotive brake shoes. The stuff I used some years ago for a brake job has the appearance of thinned-out red silicon caulk RTV. It is still in useable condition after several years and I have occasionally used it for sticking weights into rail cars etc.
I prefer steel wheels with weight for traction like real trains, but I do have a few secondhand O-gauge powered units with traction tires.