Your JTG and CS should be usable on rubber tyres as well as the foams. I've got the feeling that the JTG and CS soften the tyre a bit more aggressively than the LRP/Nosram carpet additive (could be wrong mind you).
I have virtually always used the LRP/Nosram stuff but that is mainly because the dauber bottle makes it so easy to use and it is very popular locally so the line is mostly made up of that additive.
More important than the additive is the consistency of your tyre preparation. Have a cleaning routine, time your application, think about what you are trying to acheive with the additive.
Personally speaking I always clean the tyres with lighter fluid and a towel and apply the additive for anything between 5 minutes and 20 minutes depending on what the grip level is like. I don't use warmers, don't have the time for them at club and rarely feel that I am missing out on any grip from not using them at bigger meetings. Some people also vary the width of additive on the front tyres, less additive for less steering.
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