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Hoosier Strange Wear

 
Old 11-23-2018, 02:44 PM
  #1  
Earlierapex
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Default Hoosier Strange Wear

So my 20" hoosiers did this on the inside of the both rear tires (driver's side quite a bit worse) at Sebring over 6 sessions. This has not happened with MPSCs. Sebring is clockwise, so driver's side gets a bit more abuse. My suspension is stock 2014 GT3. I'm running as much camber as possible in the rear, can't remember exactly what it was set to, maybe -1.8. Any guesses as to what is going on? I couldn't see or hear any obvious rubbing, but I wasn't really looking for it. Remainder of tire has a ton of life left, though you can see the outer edge is starting to wear like normal with "street" camber. Could it be:
1) rear wheel steering?
2) stiffer springs needed?
3) raise suspension a bit?

Thanks and Happy Thanksgiving to RL folks.

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Old 11-23-2018, 03:02 PM
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Mpsc2 wear differently than normal tires.
With cup2 I would wear the rear outer edges very quickly. With trofeoR and Re71r on same alignment the insides would wear.
Check your alignment. Probably too much camber and/or toe causing the issue. Alignment for one set of tires is not the same for other tires
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Old 11-23-2018, 04:01 PM
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I’d double check to make sure it isn’t rubbing and catching something...it really looks like something is digging into the tire. Hard to believe it simply wear that much after only 6 sessions.
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Old 11-23-2018, 10:45 PM
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Agree with above posts... something's not right.

A GT3 easily can get 2.5 to 3.5 negative camber in the rear, so I'm a bit confused by your statement 'max negative camber is 1.8 in the rear'? Maybe it's 2.8+?

And I'm still on my original set of Hoosiers, running 2.7 negative. If it's happening to both tires the same.it could be that your rubbing on something, I'd look all inside the wheel well and see if you see any rubber collection.

If not, check the rear camber alignment again... Toe & Camber... I run 2.7 negative in the rear with no issues... and a slight amount of toe in.

Best Regards,
Dave
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Old 11-24-2018, 12:05 PM
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Looks like a combination of too much toe-in and the rear steering. If your rear camber is measured correctly, you should be wearing the outer edges like that and not the inners.

Are you over sliding the rear of the car too much?

I ran 19" 325 Hoosiers down to the start of the cords in 28 20min sessions at Mid-Ohio (wanted to see how far they would go). Granted I'm not running 100%, more like 80ish and the tracks are way different obviously.
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Old 11-26-2018, 11:03 AM
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Thanks for all the ideas. I'll double check the rear alignment. I'm 90% sure I went with max stock camber and very slight toe-in, so I really doubt it's an alignment issue. Also, I didn't get this bizarre inner wear issue with 3 sets of MPSCs.

I tend to agree with the point that something is rubbing because the wear in the rubber looks unnatural on both sides, particularly the driver's side (which makes sense with 200lbs more weight and a clockwise track). I'm guessing it's probably the "bounce" at the apex in T17 in sebring, which is high G's combined with a lot of suspension movement. I may need to adjust around that dip with hoosiers as I'm clearly getting more G's and consequent roll and compression. I ordered a scope camera from Amazon and will see if I can locate a culprit.
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Old 11-26-2018, 11:30 PM
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Recheck your rear alignment and make sure you are plugged into a battery charger and the car running so you zero out the rear wheel steering. Your toe could be way off. Any vibration at speed?
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Old 01-17-2019, 05:01 PM
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So I checked a buddies 991.2 GT3 at Sebring a couple weeks ago - exact same strange wear issue on the inside of both rear tires with Hoosiers. I haven't seen this before and suspect it may be related to RWS?

Anybody else seeing this?
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Old 01-17-2019, 07:00 PM
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Originally Posted by Earlierapex View Post
So I checked a buddies 991.2 GT3 at Sebring a couple weeks ago - exact same strange wear issue on the inside of both rear tires with Hoosiers. I haven't seen this before and suspect it may be related to RWS?

Anybody else seeing this?

had the same thing after a 3-day 250 lap weekend at Mosport ...corded the inside of all four R7's ... checked for rubbing, etc and didn't see anything (static look so probably doesn't tell what s happening at speed on track)...never figured out why...dialed back negative camber (was only -2.5F/R, so I doubt that was the cause)...maybe the tires "standing up straight" under threshold braking??



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Old 01-17-2019, 07:31 PM
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My Hoosiers never did that, at negative 2.7 in the rear. I'd check inside wheel well and see if any rubber visible on something?

If it's doing it on both rears, and not rubbing, I would reduce toe, could be going excessive with RWS possibly?

Best Regards,
Dave
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Old 01-17-2019, 07:55 PM
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I've "heard" (not confirmed by any means) that this car generally works pretty well with less camber than typical, and this wear pattern *seems* to be camber related.

Dave, are you driving a GT3 or RS?
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Old 01-17-2019, 08:12 PM
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That's normal wear on Hoosiers in a 991 GT3, 991 Turbo S, 991 GT3 RS. I have been running Hoosiers on the 991 RWS the last 3 years, same issue as the pictures when I didn't know the R7 better.

It is due to excessive toe, and it cannot be fixed, even setting static rear toe to zero (a no-no for a 911).

The type of racetrack is what is going to determine if the early wear shows up. Lots of turns at more than 50mph, RWS will be working on those turns. Lots of turns below 30mph, RWS will be working there too.

To give an idea on how much toe-in (or toe-out below 31mph) RWS produces, my static stock toe-in setting in the back is 0.5 degrees total (0.25 degrees per side). When RWS is active in the GT3/GT2/RS it steers (or counter steers) by 1.5 degrees, so on 50+ mph turns, the loaded rear tire will be at 1.75 degrees toe-in for most of the turn, that's massive, 7 times more toe-in than stock. Hoosiers are not designed for RWS cars, I think most tires are not, the exception being Dunlop/Pirelli/Michelin and their work with Porsche/Lambo/Mercedes/Audi. It is even more bad in the 991 Turbo S, my TTS RWS turns 3 degrees.

Hoosiers need more camber, I run -3.2 degrees in the back and stock toe (0.25 degrees per rear corner). My Hoosiers (have gone through many sets) show these same cords inside and out, my target hot pressure in the back is 34 psi. The pictures above are from cars with little camber for Hoosiers, they need a lot.

The treaded part of my rear Hoosiers (those dotted lines in the middle two rows) are pristine, but both edges cord pretty early. I check my tires before every track session, one track session won't do that unless track sessions run for 30+ minutes.

Sebring eats Hoosiers, that's an extra factor, Sebring has an abrasive concrete, it just eats Hoosiers. I get 8 20 minutes sessions on Hoosiers before rear cords.

My front tires never cord, but if I put new rears and old fronts, the car pushes and I'm already maxed out for sway bars (I run full soft front, full stiff rear), so I have a nice collection of 235 and 295 Hoosiers that have plenty of life and grip but no longer usable.

They are still my favorite tire. Tried Yoko, Michelin, GY, Pirelli, dunlop slicks through the years, ended with Michelin and Pirelli as my preference, but 4 heat cycles and $2500 per set, no thanks.
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Old 01-17-2019, 11:59 PM
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Originally Posted by Earlierapex View Post
I've "heard" (not confirmed by any means) that this car generally works pretty well with less camber than typical, and this wear pattern *seems* to be camber related.

Dave, are you driving a GT3 or RS?
My prior Hoosier experience was 20" Hoosiers on a .2 GT3. I'll be running 20" Hoosiers now on a .2 GT3RS.

Best Regards,
Dave
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Old 01-18-2019, 11:35 AM
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Originally Posted by A/S View Post
That's normal wear on Hoosiers in a 991 GT3, 991 Turbo S, 991 GT3 RS. I have been running Hoosiers on the 991 RWS the last 3 years, same issue as the pictures when I didn't know the R7 better.

It is due to excessive toe, and it cannot be fixed, even setting static rear toe to zero (a no-no for a 911).

The type of racetrack is what is going to determine if the early wear shows up. Lots of turns at more than 50mph, RWS will be working on those turns. Lots of turns below 30mph, RWS will be working there too.

To give an idea on how much toe-in (or toe-out below 31mph) RWS produces, my static stock toe-in setting in the back is 0.5 degrees total (0.25 degrees per side). When RWS is active in the GT3/GT2/RS it steers (or counter steers) by 1.5 degrees, so on 50+ mph turns, the loaded rear tire will be at 1.75 degrees toe-in for most of the turn, that's massive, 7 times more toe-in than stock. Hoosiers are not designed for RWS cars, I think most tires are not, the exception being Dunlop/Pirelli/Michelin and their work with Porsche/Lambo/Mercedes/Audi. It is even more bad in the 991 Turbo S, my TTS RWS turns 3 degrees.

Hoosiers need more camber, I run -3.2 degrees in the back and stock toe (0.25 degrees per rear corner). My Hoosiers (have gone through many sets) show these same cords inside and out, my target hot pressure in the back is 34 psi. The pictures above are from cars with little camber for Hoosiers, they need a lot.

The treaded part of my rear Hoosiers (those dotted lines in the middle two rows) are pristine, but both edges cord pretty early. I check my tires before every track session, one track session won't do that unless track sessions run for 30+ minutes.

Sebring eats Hoosiers, that's an extra factor, Sebring has an abrasive concrete, it just eats Hoosiers. I get 8 20 minutes sessions on Hoosiers before rear cords.

My front tires never cord, but if I put new rears and old fronts, the car pushes and I'm already maxed out for sway bars (I run full soft front, full stiff rear), so I have a nice collection of 235 and 295 Hoosiers that have plenty of life and grip but no longer usable.

They are still my favorite tire. Tried Yoko, Michelin, GY, Pirelli, dunlop slicks through the years, ended with Michelin and Pirelli as my preference, but 4 heat cycles and $2500 per set, no thanks.
This is extremely helpful experienced-based input! I love rennlist, thank you!

My first thread pic is what the driver's rear tire looked like after 6 sessions at Sebring - obviously toast, and the rest of the tire looks like it's good for 5-10 more sessions. Makes sense with the grippy concrete and clockwise track. I'm curious about the camber though. I've always followed the mantra that hoosiers like more negative camber. I'm no suspension guru, but wouldn't more camber move the tire's CoG towards the inside and accelerate the RWS-toe-in-related wear? If you do the opposite (less camber), wouldn't that theoretically relieve some of the toe-in wear?

I wonder if my driving style (ahem, somewhat aggressive, ahem) makes this worse? I left-foot trail-brake a lot, which probably exacerbates toe-in, and I like to work the rear of the car (early rotation, lots of gas). Also, wouldn't the higher Gs of hoosiers likely cause more RWS earlier and for a longer period? It just makes no sense that a higher G tire would wear MORE on the inside unless something really dramatic is happening under dynamic suspension loading.

I've got the stock suspension set at max camber (can't remember exactly, roughly -2.2 all around), and the crazy irony is that the MPSCs wear on the outside first?
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Old 01-18-2019, 11:43 AM
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Mpsc wear on the outside first because they are dual compound. The outer tread is much softer than the inside. That is why even wear on cup2 is impossible. I also think that is why attempting to get even wear on cup2 with lots of camber hinders performance.
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