Triangles on the sidewall. Wut?

wondering what the little triangle is for. Tread depth? Bridgestone=rotary fans? 

Inside the tread is where the wear bars are located. The triangle points out the location from the sidewall.

Greg

Triangle indicates how far the tire should roll.  If you are getting wear past the point of the triangle you either need more air pressure or more negative camber.

^ the two answers above are the ones I've heard for years.  Every time I hear one of them I also hear that the other is incorrect- I sure would like to know which it is. I'm inclined to believe that slantsix is correct. 

Could be both. Maybe officially it's what slantsix said. Maybe unofficially it's the air pressure indicator?  

Hopefully tire roll indicator

It could be for both/ coincidental that that the triangles are radially aligned with the wear bars?

I never Thought about the Tire Pressure / Roll indicator but You learn new stuff every day!

https://www.tracknightinamerica.com/articles/2011721-under-pressure

Greg

Michelin uses a little Bib instead of the triangle. 
 

I'm in the camp for both. 

(not a performance tire, but it's what was in the garage)
 

DWNSHFT said:

Triangle indicates how far the tire should roll.  If you are getting wear past the point of the triangle you either need more air pressure or more negative camber.

Nope, not officially anyway. Though in this instance it does seem to line up with the rubber compound seam so it's pretty close. But their official purpose is only to indicate the locations of the tread wear indicators. And even if they are rollover indicators it would still just be a suggestion not a hard indicator, as that's not a "one size fits all" situation.

slantsix said:

Inside the tread is where the wear bars are located. The triangle points out the location from the sidewall.

 

Greg

This is correct.

chandler said:

slantsix said:

Inside the tread is where the wear bars are located. The triangle points out the location from the sidewall.

 

Greg

This is correct.

Not according to GRM's official tire tester Andy Hollis: https://www.tracknightinamerica.com/articles/2011721-under-pressure

Hmm. This might turn out to be a real mystery..  I say grm+ and print magazine subscribers get to find out  'fo 'sho when there is a proper article printed by Stoddard and staff to fully inform the public and dubunk the theories.

I smell an interview with (name your favorite rubber co engineer here)

Greg

Karacticus said:

Michelin uses a little Bib instead of the triangle. 
 

I'm in the camp for both. 

(not a performance tire, but it's what was in the garage)
 

You can see the wear bar in the tread in your photo (about 1 o'clock in the photo) and it doesn't even line up to the Michelin Man...

Javelin (Forum Supporter) said:

chandler said:

slantsix said:

Inside the tread is where the wear bars are located. The triangle points out the location from the sidewall.

 

Greg

This is correct.

Not according to GRM's official tire tester Andy Hollis: https://www.tracknightinamerica.com/articles/2011721-under-pressure

I worked for BS/FS, it's a Tread Wear Indicator (TWI). It should point to the tread groove for tread depth and it also tells when the tire is worn out, I've never liked this since on many tires it's worn out before this.

^^^ Wear bars.

These triangles are on 100% of street tires. And 99% of users aren't worried about or checking for rollover. 40% of users are probably running them well past the wear bars.

If the tires are bald, it still points out where the wear bars should have been.

Why would sidewall rollover indicate tire pressure?

It could also be telling you that you need more or less camber.

If ya wanna get serious, get a tire pyrometer.  

It seems like a poor indicator of proper tire pressure to me.  However, I guess it could save the edge of your tire if you c ant change your camber for whatever reason.

Crikey, it'd be stupid easy to check on the one count.  Look at tires.  Depth indicator bar line up with triangle? 

Either it does or it doesn't. 

Edit:  There is a 100% correlation between the triangle and the tread wear indicator bars on the two sets of fairly new tires in my garage.  One is Yokohama, one is Bridgestone.

Javelin (Forum Supporter) said:

Karacticus said:

Michelin uses a little Bib instead of the triangle. 
 

I'm in the camp for both. 

(not a performance tire, but it's what was in the garage)
 

You can see the wear bar in the tread in your photo (about 1 o'clock in the photo) and it doesn't even line up to the Michelin Man...

That thing at 1:00 is the winter tire "special compound" wear indicator. The actual tread wear indicator is the hump between blocks and is indeed lined up with Bibendum.

Goodyear SC3. You can pretty clearly see the line between tread and sidewall rubber (yes, I let them roll over a bit too much...oops) and it's nowhere near the indicator.

So how did the incorrect version get started, and why is it so prevalent? 

It often ends up being at or very close to the right spot (see OP image), so it's not too hard to see how that could get confused. On tires where the rubber crossover isn't as apparent it could be the only thing you have to use as a reference point. Which doesn't mean that it's actually an indicator, but you would figure out the optimal rollover point from testing and use the triangle as a reference point to track it across different setups, conditions, etc. Prevalent because, like lots of other plausible but incorrect things, one person repeats it to someone else, they repeat it to a few people.....

In reply to dps214 :

And it got repeated enough to be repeated by the SCCA in an article on tire pressure for track nights written by none other than multiple time National Champion Andy Hollis, which leads it a lot of gravitas. I first learned about it at Evo Driving School.

Javelin (Forum Supporter) said:

In reply to dps214 :

And it got repeated enough to be repeated by the SCCA in an article on tire pressure for track nights written by none other than multiple time National Champion Andy Hollis, which leads it a lot of gravitas. I first learned about it at Evo Driving School.

I was honestly surprised by that, I've definitely seen hollis correct people on that elsewhere. Then again, for the typical track night crowd the message they were probably trying to convey was more "don't let your tires roll over onto the sidewall" at which point it's much easier to say "look at these triangles" than give the full explanation.

Look at it this way...  if you have too much sidewall flex and it wears the triangle off, then what?  If it was a sidewall indicator, it would be something much more permanent.

Javelin (Forum Supporter) said:

So how did the incorrect version get started, and why is it so prevalent? 

IDK, I'd never heard it until this thread.