He's right.
The difference between a tire and a disk is that a car will run over a disk, maybe catch a little air, but come down and keep going. With a tire, the car STOPS, thanks for playing! Broken parts many times ensue.
What is fun, though, is that sometimes the car will hit the tire and bounce back out which yields some really cool T-bones and accidents as oncoming cars hit the unlucky bouncing car. . .
I would get the plastic discs before I went with tires.