What do you think about this corded V710?

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Corded a tire today and it looks unusual to me:

Stock 97 M3, right rear tire, cording on the outside half of the tire. Tire has about 80 or so runs, was flipped once about 20 runs ago. This is the only spot, all other tires look fine but well worn.

1. Is this the normal way that 710s cord on a heavy high HP car? Peel-back of relatively thick rubber in a big, big patch?
2. If it's not normal (or even if it is), what do you think was the cause?

My only prior experiences with corded tires was on a 500 lb lighter car with 60 less HP and good suspension settings. Every corded tire on that car "feathered" into the cords, and the cords usually appeared very gradually in small spots over several places on the tire. This one looks very, very different.

Thoughts?

Aaron Buckley · **Posted:** Mon May 22, 2006 8:18 am

I know a lot of people that have 710's cord like that. I'm not sure why it happens in that manner, but that is not unusual. What is unusual is it was only with 80 runs or so. Most are seeing 100+ runs out of 710's. Laurinburg is awfully hard on tires and I know you've run there a good chunk, so I guess it may not be that surprising...

You'll find pictures like that on SCCAForums with people asking the same questions when they see that 'peel back'. It kind of reminds me of how the BFG G-Force R comps used to cord. - AB

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

Any idea when that happened? You did have the rear sliding to that side on your 4th or 5th run when you hung it out coming to the finish.

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

the V700s i had last year corded like that. but even worse. like 2-3" bands around the whole tire.

Ryan Holton · **Posted:** Mon May 22, 2006 9:32 am

MikeWhitney wrote:

Thoughts?

Slow down?

Carl Fisher · **Posted:** Mon May 22, 2006 10:12 am

Aaron Buckley wrote:

It kind of reminds me of how the BFG G-Force R comps used to cord.

I was thinking the same thing...

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Aaron Buckley wrote:

I know a lot of people that have 710's cord like that. I'm not sure why it happens in that manner, but that is not unusual. What is unusual is it was only with 80 runs or so. Most are seeing 100+ runs out of 710's. Laurinburg is awfully hard on tires and I know you've run there a good chunk, so I guess it may not be that surprising...

You'll find pictures like that on SCCAForums with people asking the same questions when they see that 'peel back'. It kind of reminds me of how the BFG G-Force R comps used to cord. - AB

Thanks Aaron, that's what I was looking for. I'm a little bummed, because I was used to getting 120-140 runs out of Victoracers on the E30. However my driving style has changed a bit with the M3 -- sometimes the only way to get it "handling" properly is with a little rear tire spin. So I'm much more aggressive in the M3 than I was with the E30 325is, and I strongly suspect this is the root cause of the high wear and the big corded patch.

I'm starting to mentally calculate how long it would take for a good suspension on this car to pay for itself in tires. I'm sure that I would be able to drive more smoothly and I'd probably be back in the 100+ runs on a set of tires.

One thing I think I learned is that I flipped the rear tires too late at 60 runs. The inside half of the tire wears much faster than the outside edge because of all the tire spin. That "thin" part is what corded, now on the outside, on that tire. I need to do it at about 40, not 60. The fronts however are about perfectly worn... But I'll need to toss them anyways -- the wear indicators are gone, probably very little life left in them.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Wes Eargle wrote:

Any idea when that happened? You did have the rear sliding to that side on your 4th or 5th run when you hung it out coming to the finish.

Not sure when it happened, but it may have been there and getting worse all day. My times certainly reflect that -- my first was my best and every successive run was slower. All 5 are within 0.5 seconds though!!!

48.021
48.026+3

48.346
48.368
48.496+1

Kendra ran after my 2nd run. So it might have started then -- that would help explain the 0.3 second increase in times with little or no other changes.

Kendra's times would support the conclusion that it started on her 2nd run also:

53.042
51.951

52.611+1
52.499+1
53.117

Keith Quistorff · **Posted:** Tue May 23, 2006 1:56 pm

MikeWhitney wrote:

One thing I think I learned is that I flipped the rear tires too late at 60 runs. The inside half of the tire wears much faster than the outside edge because of all the tire spin. That "thin" part is what corded, now on the outside, on that tire. I need to do it at about 40, not 60. The fronts however are about perfectly worn...

Mike - IIRC, you're running the same size tire on front and rear, just staggered wheel widths, correct? If so, you should be able to better balance wear also by swapping the tires front to rear when you flip them (or instead of flipping them, assuming your fronts wear more on the outside edge).

Chuck Branscomb · **Posted:** Thu May 25, 2006 9:48 pm

Mike,

Misc random thoughts...

From what I've seen at track events, this is nothing unusual. On Saturday when I was at the Goodyear place in Danville getting a flat repaired (my daughter ran over something at the Chick School causing a minor leak), I did see a very unusual cording off a 996TT left rear tire where just two spots about 2" long were corded on the outer edge. The car was running 2+ degrees negative camber on the rear with inside tire wear also, and there was no evidence of bodywork contact. BTW, the Goodyear place totally surprised me with the skill in mounting race tires on rims without damage doing mine and also the monster rears on the 996TT plus one other guy from VIR.

Any idea how the V710 compares to the A6 in terms of tire life and grip? Later this year or next season, I'm pondering switching to a real auto-x R-comp tire and doing the "changing at the event" deal. These Dunlop SSR R-comps are very nice in that they wear forever, and I can drive to events on them; however, they are more suited to a track event similar to an RA1 (even if Tire Rack did sell me a set with a 4 year old date code

).

I'm sort of assuming the A6 is the tire to get, but with my daughter co-driving the events, I'm wondering how many runs we'll get out of them. Which takes me right back to the thought of getting another set of semi-serious R-comps like RA1's for tread life and drive to the event usability. Too bad they don't come in 245/35-18 since I would have to again run 225/40 all around with those two.

Regards,
Chuck

Emmie Fisher · **Posted:** Thu May 25, 2006 11:01 pm

MikeWhitney wrote:

Thoughts?

I don't see any wire. I think you can get another event out of it. :wink:

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Branscomb wrote:

Any idea how the V710 compares to the A6 in terms of tire life and grip? Later this year or next season, I'm pondering switching to a real auto-x R-comp tire and doing the "changing at the event" deal. These Dunlop SSR R-comps are very nice in that they wear forever, and I can drive to events on them; however, they are more suited to a track event similar to an RA1 (even if Tire Rack did sell me a set with a 4 year old date code

).

Chuck - I may not be the best to ask because I'm admittedly pro-Kumho and anti-Hoosier just based on my own dated experience with some old Hoosier R3's and talking to people about their experience with Hoosiers. I have no other experience w/ A5s or A6s. I *will* tell you that I'm quite pleased with the performance and in general the wear of the 710s. Even with terrible suspension geometry they have been wearing evenly and I'm not having any problems with cording the outside edge. From what I understand, you can't expect much life out of the Hoosiers unless you have lots of negative camber. I'm not sure what suspension you're running. Anecdotal evidence also suggests that Hoosiers tend to heat cycle out and become less consistent much faster than a Kumho.

Thus, I'd recommend 710s for anyone running less than optimal alignment and suspension, and for someone who values consistency. I'd recommend Hoosiers for people with good camber adjustability and wants a fast tire that may need to be retired early.

BUT!!! As I mentioned I have no experience with autocross Hoosiers and I have grown to really, really trust Kumhos. IMO, YMMV, etc. I'll let others argue about what I have said above! Hey, you asked for the advice

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Keith Quistorff wrote:

MikeWhitney wrote:

One thing I think I learned is that I flipped the rear tires too late at 60 runs. The inside half of the tire wears much faster than the outside edge because of all the tire spin. That "thin" part is what corded, now on the outside, on that tire. I need to do it at about 40, not 60. The fronts however are about perfectly worn...

Mike - IIRC, you're running the same size tire on front and rear, just staggered wheel widths, correct? If so, you should be able to better balance wear also by swapping the tires front to rear when you flip them (or instead of flipping them, assuming your fronts wear more on the outside edge).

You're right Keith. I'm an idiot and I never even considered swapping tires front to rear when changing ... I'm new to stagger! Thanks for pointing that out!

Chuck Branscomb · **Posted:** Fri May 26, 2006 6:58 am

Thanks for the reply Mike. The suspension on the 2003 330i is pure stock (ZHP package), so there is very little camber adjustability up front. Supposedly BMW added 0.5 degrees negative camber to the ZHP compared to the standard 330i (not sure specifically which parts were modified), and you can slightly move the struts inward such that I ended up with -1.4 degrees of negative camber when I had it aligned. Hence, it is definitely camber challenged and probably would eat up the Hoosiers as you mentioned. It sounds like the 710 is the way to go.

I'm stuck with the stagger issue also. I bought some new rims for race tires but had to go with 8" front and 8.5" rear, so I can't rotate front to rear without remounting.

Pondering the cording picture you posted some more, I'm thinking that as the tread depth wears thinner, at some point the transient thermal capacity of the tread is reduced to a level where what is left is easily locally overheated. The fact that it locally overheats and chunks off the carcass is probably typical. The tire is likely at its best, in terms of heat capacity and internal heat transfer ability, when it is new since it has the largest mass of rubber (thermal capacity) and the highest cross-section of material (intra-tread heat transfer -- reduces local hot spot temp levels).

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Branscomb wrote:

Pondering the cording picture you posted some more, I'm thinking that as the tread depth wears thinner, at some point the transient thermal capacity of the tread is reduced to a level where what is left is easily locally overheated. The fact that it locally overheats and chunks off the carcass is probably typical. The tire is likely at its best, in terms of heat capacity and internal heat transfer ability, when it is new since it has the largest mass of rubber (thermal capacity) and the highest cross-section of material (intra-tread heat transfer -- reduces local hot spot temp levels).

Yes, but the odd thing about this tire is that it corded so much differently than anything else I have corded. "710s just do that" is apparently the answer. Different construction/materials will cord differently it sounds. Who knows exactly what the explanation is. I'm sure there are many different factors. Rubber CTE, adhesives used, bonding properties, toughness of the rubber, etc, etc.

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