What do marbles have to do with auto racing? Well, the shiny round glass things are not what we’re talking about. Racing (slick) tires are designed to melt down a bit when they get hot to get super sticky. Because of this, they tend to shred themselves as if you took a cheese grater to a block of cheese. When a tire shreds and gets left on the track, that can reduce grip. Think of the analogy of leaving a bunch of real marbles on a hardwood floor and then trying to walk on them. You slip and slide everywhere. Rubber tire marbles tend to have the same effect on the race track. Typically, they’ll get chucked off of the racing line which is fine as long as you’re on the racing line. However, if you make a mistake and go wide or if you have to go off-line to make a pass on a competitor in front of you, you will undoubtedly find yourself slipping on the marbles. Not only do they reduce cornering grip, but they will also increase your braking distances.

However, strangely enough, when it rains, the marbles off-line can actually increase grip. It has more to do with the racing line being smooth with tire rubber being driven and rolled into the surface to create a smoother surface. Off-line, the asphalt pavement still has quite a bit of sharp and rough bits to enhance grip when it’s raining. The marbles can actually be a spot of water displacement which can also help with grip.

On hot days especially, marbles can build-up in radiator openings becoming a bane to your cooling system. Marbles will also punish your paint (or wrap) on the car and driver’s helmet (if in an open cockpit car). Trying to remove those black marks and streaks is enough work to keep a person busy full time between sessions to keep the car clean. Bug and tar remover and multiple other chemicals can be used to keep the surface clean and black-streak free. However, when the car is pelted at high speed, sometimes you’ll find that the paint surface has been chipped and scratched from these rubber projectiles. Sometimes, that just doesn’t “buff out.”

Lastly, if you have a new race fan visiting the track, picking up a few of these marbles at the end of a race weekend and rolling them into a tire shaped ball make for a super cheap (Free!) souvenir!

 By Larry Mason

Copyright © 2022 Larry Mason


The marbles fly off the tires and track on Shoreline Drive at the 2022 Acura Grand Prix of Long Beach.

Marbles bunch

Here’s a handful of marbles that have been removed from the grille opening of a race car

Marbles single

A single “marble” that was peeled off of the author’s helmet!

Photos Copyright © by Larry Mason