Grinding the Tunnel (Into Dust) is an achievement in Run 3. It was suggested by NintendoPanda101.
(Note: Since you can only earn this achievement with the Skater, he will be the only suggested character.)
There are quite a few different routes that will lead to success. The strategy here is to use the crumbling tile platforms instead of the normal platforms (it's as simple as that). It is possible to complete this achievement without touching a single regular tile, although you can still use them at your aid.
The first two crumbling tile platforms are crucial in order to be able to land the third and fourth. The second one, especially, must be landed on in a way where you it is possible to hit the third crumbling platform (let's call the really small platform the third platform, and the long spiral one the fourth). Don't worry about not hitting the fourth platform right when you see it because the third one is your priority (it is a very small platform, so you can easily miss it). Once you have landed on the third, jump to the fourth. Finally, jump on the final two platforms and this achievement is all yours!