Many of the classic skateboard items have an improper grip in their R15 version, causing them to stick into the arm.
For example, the ROBLOX Skateboard.
For an example of the proper grip attachment, there is the Slime Skateboard.
This issue is extremely widespread, happening to nearly all of the skateboards on the platform. I have included a list of them below.
List of effected accessories
ROBLOX Skateboard
Cartoon Network Skateboard
Red Grind Skateboard
BC Skateboard
TBC Skateboard
OBC Skateboard
Ultimate Slide Skateboard
Summer 2014 Skateboard
Digital Green Skateboard
TMNT Skateboard
Halloween Skateboard
Fancy Skateboard
Dollar Sign Skateboard
Graffiti Skateboard
Radical Orange Skateboard
Dastardly Skate
Blue Yonder
Lava XD
Orange You Jealous XD
The Unstoppable
Scribbly XD
Ameriboard