But wouldn't automatic flames popping out affect what happens when you put the tire on the car?

Other than possible interference with the free spinning nature of the tire (which is important, given that it's a tire), the interaction with the DX Trideron that MnemonicSyntax mentioned - or the fact that it's nice to have the option of having the flames either deployed or undeployed...

Looking at the newest video, the only real flaw I can say the TK Series has is that it only has 2 Tires to use out of the box. They could've placed one more in that packaging, but beside from that I actually enjoy the Series the more I look at it.