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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > Weird R-Comp wear



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      11-13-2007, 11:49 PM   #1
leftcoastman
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Weird R-Comp wear

I took my Victoracers off tonight to examine the damage from two days of hard track abuse.

With stock 335i suspension with H&R rear sway, on 17x8.5 wheels, I am getting a most unusual wear pattern on the 255-40-17 tires.

First, the rim size is the minimum recommended for the 255 tires, but that doesn't explain the wear pattern. Given the stock front camber, you would expect the OUTSIDE to get beat to hell. But as you can see from the attached pics, the insides got worn down and while the tread is more "gone" from the outside, the outside appears to have more rubber left!

The left side of the tire, as seen in the attached pics, is the outside edge. The tires were rotated throughout the weekend, and they all look like this. Thoughts?
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      11-14-2007, 08:09 AM   #2
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Let me take a pic of my pilot sport cups for comparison...
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      11-14-2007, 08:12 AM   #3
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What pressures were you running? Did you measure the tire temps at all?
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      11-14-2007, 09:12 AM   #4
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Quote:
Originally Posted by White05X3 View Post
What pressures were you running? Did you measure the tire temps at all?
Pressures were 40 hot front and 42 hot rear. Any less in the front and I'd be scrubbing the logos on the outside.

Any less in the rear and I'd be rotating like a top. Note the front and rear have pretty different camber settings - but I was rotating the tires around all weekend.
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      11-14-2007, 09:48 AM   #5
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Quote:
Originally Posted by S4to335 View Post
Let me take a pic of my pilot sport cups for comparison...
I will take a pic of my Nitto NT01's tonight also. They've been through 3 track events now.

Left,

I know you rotated them, but what are the characteristics of the track you went to? We should all post our alignments as well.
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      11-14-2007, 10:01 AM   #6
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Heg - the track was rougher than a teenage kid's face.

My alignment is bone stock. Haven't changed a thing. I did notice that the rear sway "forces" the alignment to retain it's negative camber. On my street tires, the inside edge of the rears got corded before anything else.

Of course, for the front street tires, I corded the shoulders first - two sets to be exact.

Who loves understeer?
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      11-15-2007, 10:32 AM   #7
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Quote:
Originally Posted by leftcoastman View Post
But as you can see from the attached pics, the insides got worn down and while the tread is more "gone" from the outside, the outside appears to have more rubber left!
Looks like tire pick up to me, some of which is still there and the rest got scrubbed off
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      11-15-2007, 11:02 AM   #8
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Quote:
Originally Posted by elbert View Post
Looks like tire pick up to me, some of which is still there and the rest got scrubbed off
Nah that was just on the "lip". The whole outside tread chunk is a few mm higher than the rest of the tire.

Anyone get their pics taken yet?
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      11-15-2007, 11:21 AM   #9
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Quote:
Originally Posted by leftcoastman View Post
Nah that was just on the "lip". The whole outside tread chunk is a few mm higher than the rest of the tire.
Oh I see, your picture is kinda crooked.

Did you consider the possibility that the wear might have occurred when the tires were in the back?
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      11-15-2007, 11:31 AM   #10
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Yup, but generally I spin one rear tire. Although I rotated, I only did it once so only two tires ever got put in that offending position.

All tires have this weird staircase wear pattern.

The ODDEST part is that the "higher" outside edge is devoid of tread blocks now while the inside edge (lower in absolute rubber depth) still has tread blocks.
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      11-15-2007, 11:51 AM   #11
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Quote:
Originally Posted by leftcoastman View Post
Yup, but generally I spin one rear tire. Although I rotated, I only did it once so only two tires ever got put in that offending position.

All tires have this weird staircase wear pattern.

The ODDEST part is that the "higher" outside edge is devoid of tread blocks now while the inside edge (lower in absolute rubber depth) still has tread blocks.
You're probably spinning the rear tires more than you think.

I'm willing to bet the staircase pattern is because you are running minimum wheel width. It's minimum, not optimum, as it allows a lot more sidewall flex.
Out of curiosity, do you shave the tires?

Are the channels of equal depth when new? Or maybe some tire pick up filled in the tread?
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      11-15-2007, 12:22 PM   #12
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Quote:
Originally Posted by elbert View Post
You're probably spinning the rear tires more than you think.

I'm willing to bet the staircase pattern is because you are running minimum wheel width. It's minimum, not optimum, as it allows a lot more sidewall flex.
Out of curiosity, do you shave the tires?

Are the channels of equal depth when new? Or maybe some tire pick up filled in the tread?
Yes, the minimum wheel width. And no, not shaving the tires.

And I'm an idiot - I just realized that the outer blocks had significantly shallower grooves than the rest of the tire.

Maybe what's happening is that the outer wears to "slick status" quickly and now has a ton of rubber on the road. The center/inner is still running on treadblocks so wears down a lot faster. But only thing is that I haven't heard this problem from other people running this tire.
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      11-15-2007, 12:41 PM   #13
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Were they properly heat cycled?
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      11-15-2007, 12:44 PM   #14
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Quote:
Originally Posted by HyperM3 View Post
Were they properly heat cycled?
Yes
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      11-15-2007, 12:46 PM   #15
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Quote:
Originally Posted by leftcoastman View Post
Yes
Could be like what you said you noticed. That the tires were designed for the shoulders to wear quicker so they get slick and put down more of a solid patch.
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      11-15-2007, 01:43 PM   #16
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Quote:
Originally Posted by HyperM3 View Post
Were they properly heat cycled?
He breathed really hard on them...
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      11-15-2007, 01:47 PM   #17
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Quote:
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He breathed really hard on them...
Nah - I rubbed the tires with my hand. You know how when you rub your hands together they get warm? Kinda like that.

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      11-15-2007, 02:39 PM   #18
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My Victoracers on my RX8 looked like that initially. I got more even wear and better performance when I lowered the pressure.
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      11-15-2007, 03:03 PM   #19
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Quote:
Originally Posted by davig View Post
My Victoracers on my RX8 looked like that initially. I got more even wear and better performance when I lowered the pressure.
That's comforting to hear. Did you get squirm when running really low pressures? And when you say, what's the hot pressures?

Also, did you have good neg. camber up front? My camber is so bad that I feel like I'm going to rub the wheel face on the ground, lol.
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      11-16-2007, 10:45 AM   #20
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Quote:
Originally Posted by leftcoastman View Post
That's comforting to hear. Did you get squirm when running really low pressures? And when you say, what's the hot pressures?

Also, did you have good neg. camber up front? My camber is so bad that I feel like I'm going to rub the wheel face on the ground, lol.
RX8 is camber challenged as well. I have Tein coilovers which improved things a bit. I start with 34 cold pressure all around on 245/40/17s and bleed off a bit if it gets >40 hot. It's a lighter car so I don't think you can compare pressures. On hot days I get a bit of squirm after about 12 miles. Have you tried using a pyrometer to messure temps on outside middle and inside of all tires immediately on returning to the pits? You might be hotter in the middle. I had to do quite a bit of experimentation to get even temps.
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      11-16-2007, 11:37 AM   #21
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That does not look too bad. It is typical for the tread just prior to a water channel to have some more uneven wear as the forces flex the rubber during cornering. Right of the channel wears in and left of the channel wears out and up.

Here are pics of the Nitto's after this weeks event and 6.5 hours of track driving with 500+ miles of street driving. First pic is newly scrubbed non shaved tire with six laps on them. Next is front tire and last is rear tire.
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      11-18-2007, 05:14 PM   #22
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Here are my NT01's after 5 days worth of sessions. I'm still staggered, so I can't rotate, and the last track I ran at is hell on the right side.
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