Will fit a NASCAR tyre if you so desire. It says suitable for solo 2 & 3 but don’t be fooled. 3 sizes of earpiece coverings come with it. I even wear these outside in the winter (in Canada) when taking my dogs out at night and they are super warm (Im bare foot too). It’s actually really cute, it does not have to be just for shoes. I stand on my feet for about nine hours a day so I needed a pair of shoes that are comfortable. When I hit “play” on my music it simply chooses which headphone to play out of. Worth the upgrade from original G Pro Keyboard. And it wasnt too hard to put it on. The tabs holding the laces are felt under the arch and side of big and pinkie toes.