at my local track I've seen people true their rubber tires. about 2 years agoo i guess and never seen it since. but the benefits are that you create a fresh layer of rubber thats almost as sticky and fresh as when you open your bag.
Love the smell of Frech rubber heh
also you can flatten the tire a bit, But its Really difficult to true a rubber tire because it is a bit bold compared to a Foam tire. its like trueing the rounded edges of a foam tire with your lathe. But it can be done.