What causes a tire to squeal?

[DriveHard]

Ok, the question is more complex than that. I was thinking back to some tires I have had, and switched away from. No matter how you slice it, if you get a tire to make some noise while turning, or under spirited braking, it attracts attention...especially that of your family or SO. We have a few round-a-bouts I like to navigate during trips to the local store, and I can always use it to my defense - "what, the tires didn't even squeak" ;-)

I was leaving a comment on another thread about a certain tire, and it brought back memories of tires that would squeal, squeak, whatever (not howl, that is tread), under spirited driving, and it was always a turn off. I know the mechanism...a stick-slip condition that causes a vibration, most likely close to the resonance of the tire itself. What I don't know is why some tires tend to make more noise at the limit as compared to others?

Is it the level of silicate additive in the tire that changes the stick/slip characteristics? Is it just the hardness of the tire? I will admit it seems harder tires (tires with a longer projected life) have a much higher tendency to make noise as you approach the limits. Is it because they have more carbon and are just sticking/slipping on the surface, and not shearing material away?

Ok, I could theorize all day - be great to hear from the experts.

 

[MRC01]

Some tires squeal, others do not. In SCCA racing I discovered that most DOT legal R compound tires (Hoosier, Kumho V700, BFG R1, etc.) do not squeal. Most street tires do squeal, but in different degrees. The OEM tires on my Mazda squealed loudly, the Continentals I replaced them squeal much more quietly.
When tires do squeal, they typically only do so when they're in the boundary zone between sticking & slipping. Once they go full slip, or full stick, they stop squealing. This leads me to assume the squeal is sticking & slipping repeatedly at a fast rate, creating some kind of resonance. Since R tires don't squeal, if squealing is a resonance it could be related to the tread blocks (which on R tires are much shallower, or don't exist at all).

 

[Jetronic]

Yes but my hankook v12 didn't stop squealing even while i ran them bald. Those squeal like a stuck pig btw... and way before you reach the max speed through the corner. Don't remember them doing it while braking

 

[IndyIan]

The terrible OE uniroyal tigerpaw tires on our 03 Tracker squealed the outside front tire turning sharp slowly in a parking lot..... Better tires I find don't squeal until you are really sliding.

 

[jurko]

My FL tire squeals when I make 90° RH turn at around 20mph. No squeal when I make same LH turn.

 

[hemitom]

Biggest cause.
A Heavy Foot !

 

[DriveHard]

Biggest cause.
A Heavy Foot !

My foot has nothing to do with how fast I turn my steering wheel...

 

[CapriRacer]

First, as was pointed out, squealing is a vibration. The key is that it is a higher frequency than what one feels (as opposed to what one hears.)

Some tread patterns produce more noise than others. If there are tread elements, or if there are portions of the tread elements that are small and/or pointed, those add to the noise.

Then the is the road surface. And on top of that, there is an interaction between the road surface and the tread pattern.

Soft tread compounds vibrate at lower frequencies than stiff compounds.

Needless to say this is complex and there will be contradictions - where a given tire performs worse than another tire on one road surface, but better on another.