Rebadged? What do you guys think? However, they are a spec chosen compound to keep things simple. Also, new rear tire and older Tamiya front rubber tire has proven to work well too. Especially in conditions where the track is lose.
It wouldn't be the first time Tamiya had another company make tires for them...back in the F201 days Ride made tires for Tamiya. There is nothing wrong with that...in fact it is usually a good thing!