TIRES........Corded inside edge and outside at the same time???????
 

(Pictures Added - Left side is outter side in each picture)
Long:
(Tires Hoosier R80/100 265 front, 305 rear)

I've mentioned my tire woes before (cording inside edge of left rear), but now it's gotten to the point of craziness. I ran a Barber a few weeks back and due to the blowouts prior to I dialed the camber back to 2.2* (from 3.0) with some Toe In (can't remember if it was degrees, minutes or inches so I'm not going to try to say how much, but it's not excessive). Well it was evident after two sessions that I did not have enough neg. camber as I my heat marks were well over the edge of the tread. Needless to say the tire was showing cords on the outside by the end of the day.

However upon looking at the tire as I got the replacements ready for it, I realized that I had also corded the inside edge as well. The rest of the tire is pretty even across, slight tapered upwards towards the inside. (*Also replaced rear wheel bearings recently just in case).

I'll take some pics when it's light out, but this is ridiculousness.

HOW IS THIS POSSIBLE!!!!!??????

My tire temps at Barber were normal range, in fact not even up to alarming degrees. (180's tops) and were HOTTER on the outside edge as you would imagine with not enough camber.

How then does one cord the inside edge while cording the outside edge and everything in the middle look ok?

Should I go to zero toe? Is my car too heavy (3600 lbs with driver, full tank), combined with my Getty wing?


PS: This is only the drivers side, I have not had one problem from a passenger side tire all year. The only track I had no problems from was TGP running CCW (with -2.0 rear camber, car wont turn). All the rest are CW.

PS#2: I also ran Kuhmo V710's on the second day at Barber and though they struggled on the outsides as well, they did not taper on the edges, and have not corded. I intend to run them again in two weeks at Barber with more negative camber. I was going to take more Hoosiers as back-ups, but it seems to be pointless.

Increase your tire pressures (and add back in the camber)

I run Goodyear slicks, not Hoosiers ... but if my tires were wearing on the inside/outside and not the middle, I'd be thinking about underinflation.

Scott

Are you heavy on the curbing? A couple of the guys I run with were perplexed with some unusual tire wear at thunderbolt this season... turns out it only affected the guys that hit the curbing aggressively all the time and mostly on the passenger side outside edges.

Dez, Hoosier slicks are very thin, much more so than the V710's. So IMO it's a combination of a VERy heavy car with lots of rear-biased power, not enough air pressure or camber, and your recurring slight left rear inside rub which exacerbates a very thin tire carcass.








Professional Racing and Driving Coach

I ran 30 psi in the rear. Didn't know if it was safe to go higher.

I only use one curb at Barber, but it is on that side going down through the museum turn. It always caused ABS lockup in the front as the grip on the curb isn't the same as on the actual track surface.

Dave, I reduced the tire size since the last incident, the last size was 320's and they may have rubbed, but the 305's aren't even close to rubbing (a full inch less width).


I'm just going to run out these last ones I have and accept the fact that I can't run slicks on my car.

:confused:

I completely agree with too low tire pressure. You are 10-14 lbs (hot) too low on the rear.

I would have to run R80's and R100's at 40-44 lbs then?



Pictures added, left side is outter, and right side is inner in each picture.

+1 more on too low pressure... I'd be in the 36 pound hot range.

Not the same tire but when spec was running on 888's we saw some weird treadwear that alternated between scrubbing the shoulders to the cord or burning through the third point on the tread (which looks a bit like your pictures) oddly both caused by low pressures. You'd either be sitting on the shoulders and wearing them out, with a bit more pressure it moved the wear off the shoulders but the tread wasn't supported with enough pressure so the tread face would roll and create a pattern that looked like overinflation but off center, with additional pressure you would get back to even treadwear. Once everyone saw the signs of overinflation we'd back off pressures when the solution was more...

I run my Hoosier slicks at 30 hot though I'm 1,000 lbs. lighter than you. Your tires are definitely talking to you and they're shouting "give me air, give me more air". There appears to be plenty of tread depth on the outer holes, they're just screaming for more pressure. I'd try that first without changing anything except I'd run the rears at 36-38 hot. I'd spray the tires with red or yellow marker paint across the entire face and up onto the sidewalls. That will show you if you're rubbing and mark the places it touches....

Ok, I'm going back to Barber in two weeks. I'm going to put a set of Hoosiers on to test this theory. I'll report back. Also going to take about 150 lbs out.

Thanks for the help.

Definitely would go up at least 5lbs of pressure in those tires. In lighter cars you can get away with less pressure, but not yours.

Definitely need more tire pressure. Those tires look severly grained IME.

http://www.hoosiertire.com/pdfs/tctR6_A6.pdf

A lot of guys run Hoosiers too soft. They feel like they have lots of grip, but there is more as they get harder from more pressure. Problem is that just at the point where they work best, it only takes one more pound & they go over the top (i.e. get greasy).

My data point with the RSA was that R6s were about .5 seconds quicker at 37/38 lbs than at 35/36. At 39 they stopped working.

In reference to the 4th picture I would say the slick carcass is coming apart on the inside, causing the strange lump around the tire. We have seen this happen but on a much larger scale to a set of falken slicks one of our customers used. I will try dig the pics up once I'm at work today.