1 2
Vajingo
Vajingo HalfDork
6/11/21 10:22 p.m.

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

slantsix
slantsix Reader
6/11/21 10:31 p.m.

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

 

Greg

DWNSHFT
DWNSHFT Dork
6/12/21 7:13 a.m.

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.

ShinnyGroove (Forum Supporter)
ShinnyGroove (Forum Supporter) HalfDork
6/12/21 7:19 a.m.

^ 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. 

Vajingo
Vajingo HalfDork
6/12/21 7:55 a.m.

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

fusion66
fusion66 Reader
6/12/21 8:08 a.m.

Hopefully tire roll indicator

slantsix
slantsix Reader
6/12/21 8:16 a.m.

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

Karacticus
Karacticus GRM+ Memberand Dork
6/12/21 8:43 a.m.

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)
 

dps214
dps214 Dork
6/12/21 8:55 a.m.
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.

chandler
chandler UltimaDork
6/12/21 9:35 a.m.
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.

Javelin (Forum Supporter)
Javelin (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 9:59 a.m.
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

slantsix
slantsix Reader
6/12/21 9:59 a.m.

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

Javelin (Forum Supporter)
Javelin (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 10:01 a.m.
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...

chandler
chandler UltimaDork
6/12/21 10:10 a.m.
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.

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
6/12/21 10:41 a.m.

^^^ 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.

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
6/12/21 10:42 a.m.

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.

1988RedT2
1988RedT2 MegaDork
6/12/21 10:44 a.m.

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.

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 11:05 a.m.
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.

dps214
dps214 Dork
6/12/21 11:17 a.m.

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.

Javelin (Forum Supporter)
Javelin (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 11:18 a.m.

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

dps214
dps214 Dork
6/12/21 11:36 a.m.

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.....

Javelin (Forum Supporter)
Javelin (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 11:47 a.m.

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.

dps214
dps214 Dork
6/12/21 12:06 p.m.
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.

racerfink
racerfink UltraDork
6/12/21 12:25 p.m.

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.

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
6/12/21 12:38 p.m.
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.

1 2
Our Preferred Partners
Kn0iSZFTdfCsbKvaZpOJ5vAOrgRnsSdicBV8xuG2UjOeeiO2vXic5NphMsqJnE8s