Since 2016 we have allowed a free choice of tyres in all classes. Most often, this means NSR tyres are used to take advantage of their steroid-enhanced grip levels. Beware, though, that they do require a bit of upkeep and won’t thank you for running two heats back-to-back without cleaning in between.
The best idea is to run your car on its standard tyres and then see whether you are short of grip. Ninco track works very well with Ninco and SCX tyres, and many of the Spanish and Italian manufacturers base their setups and tyre compounds on the very same surface that we use.
If you want to change rubber, here is the sizing guide for NSR tyres.