tires: tread seperated/split

T77911S · 10-29-2019, 05:53 AM

took the BMW to the track this past weekend and the tires split/ tread is separating.
brand new (yes cheap sumitomo) tires.
just curious if anyone else has had this happen.
cold pressure was 32, hot hit 46 on fist session.
kept dropping air pressure until finally got the hot pressure down to 38-42.

was doing tire temps, hottest was 160-165.
temps did show too much pressure
I don't have the chart in front of me to post numbers,
just curious, what are the hot temp pressure you guys tend to run.

Driven97 · 10-29-2019, 06:32 AM

Yeah I don't think that tire was designed to work at those temps. I've delamed an old semi-sporty BFG in the 90s that way, and a set of Kumho V720s a few years ago as well.

Since then Kumho has removed any mention of track / autocross in any V720 advertising. Junk.

I don't think you could've saved that tire for track work with anything other than backing off and driving slower. Pressures aren't what did it in, just not a track capable tire.

T77911S · 10-29-2019, 06:38 AM

the front left did it too, but just a little.

I felt the left rear go.
funny thing is I had felt kind of the same thing in the 930 when cornering but the tires did not do this,.
I have the conti extreme contact on the 930 now.

theiceman · 10-29-2019, 06:45 AM

hmmmm cheap Chinese tires ....

I think ill go to the track with these tires ...

what could POSSIBLY go wrong .. lol .....

i think you were very lucky.

Arne2 · Arne2's Garage

To be fair, most Sumitomos are made in Thailand, not China. But still...

porsche930dude · porsche930dude's Garage

Id contact sumitomo and see what they have to say about it. At the very least they will be made aware of it and help them improve. Believe it or not they appreciate feedback like that

T77911S · 10-30-2019, 02:49 AM

they said contact the people I bought them from.

tire rack did take the info about the tires, track, tire temps, pressures and such.

eastbay · 10:39 AM

Tire tread 'chunking' in full tread depth tires is a well understood problem in autocross and racing. Shaving the tire depth has been done for years and years with even racing compound tires being shaved to avoid this. User error.

RWebb · RWebb's Garage

what is the date code??

911pcars · 10-30-2019, 03:36 PM

Sumitomo is a Japanese brand name. They could have been manufactured anywhere Sumitomo has contract sources. Still, their specs.

Sherwood

T77911S · 10-31-2019, 03:07 AM

Quote:

Originally Posted by eastbay

Tire tread 'chunking' in full tread depth tires is a well understood problem in autocross and racing. Shaving the tire depth has been done for years and years with even racing compound tires being shaved to avoid this. User error.

that's what I was wondering about. the tread seems very tall on these and they are brand new. I was thinking that because the tread is so tall that there is more leverage to rip the tread from the tire.
my other thought was the suspension is stock and I drove the piss out of and with all the lefts it wore the outside edge enough to rip it off. I will have to post pics later.

only second time on track.....

going to NCM this weekend, putting 2 new tires on, just going to have to go slower.
yea, like that will happen

Driven97 · 10-31-2019, 03:54 AM

In that 245/40-17 size try the Hankook RS4 instead. Very track day capable but still with good street manners. $653/set from Tire Rack.

If track days are a very rare thing, you could probably get away with something like a Continental EC Sport. $696/set from Tire Rack. Amazing street tire and works great in the wet, and can hack it at an occasional track day.

If you want to go cheaper you can try the Federal 595 RS-RR, currently $524 for s set of 4 shipped from Simple Tire. I haven't run that particular tire, but I had the previous model 595RS-R and it was amazing for the price. I hear the RS-RR is quite loud on the road though. Fine on an old 911 where you can't hear anything over the mechanical & wind noises anyways.

T77911S · 10-31-2019, 06:57 AM

yea was just planning this one track day in the BMW, that's why the cheap tires.
then my brother talked me into doing NCM this weekend.

I have all the 930 engine parts at machine shop now so hope to get that going soon, also have an old circle track late model I am really considering making it into a road course car.
need to put in passengers seat and do some frame work on it.

eastbay · 08:21 AM

You mentioned the problem in your first post, You kept lowering the tire pressures until the tires failed. Ignore hot tire pressures.

Read up on tire chalking (or use a cheap IR temp gauge)

Start with a much higher cold tire pressure than what you used since you have wear past the tread and up on the sidewall.
( I'd start in the mid to lows 40s)

For example, I used to run a B/SP V8 car with shaved R1 tires and my initial cold pressure was 60-65psi on the front tires.

Good luck, it is all a balancing act. It's not racing if you're not ruining stuff.

onboost · 10-31-2019, 08:14 AM

Don’t get me started on this. although not a track car.. or a car even, but I Just had a massive tread separation on my dually with Michelin tires… I was shocked, and pissed.

The tread actually separated from the sidewall although tires are still holding air. The sidewalls are cracked and dry-rotted.. and no, I’m not sure of the age. However, I’m glad I wasn’t on the road. This actually happened while the vehicle was sitting and it’s not the first time I’ve had issues with Michelin sidewall deterioration although the tread had plenty of life left.

Rusty Heap · Rusty Heap's Garage

Sharp eyes spot your heat problem.

You took the photo on your BBQ?

T77911S · 10-31-2019, 08:32 AM

naaaa,
bed liner of pickup.

dannobee · 10-31-2019, 05:03 PM

Are you sure it wasn't just the tire rolling over because of not enough static negative camber and really low tire pressure?

And when you took tire temps, did you go all the way over past the edge, or just on the tread?

911pcars · 11-01-2019, 11:12 PM

Quote:

Originally Posted by onboost

Don’t get me started on this. although not a track car.. or a car even, but I Just had a massive tread separation on my dually with Michelin tires… I was shocked, and pissed.

The tread actually separated from the sidewall although tires are still holding air. The sidewalls are cracked and dry-rotted.. and no, I’m not sure of the age. However, I’m glad I wasn’t on the road. This actually happened while the vehicle was sitting and it’s not the first time I’ve had issues with Michelin sidewall deterioration although the tread had plenty of life left.

Age could be a factor (date stamp on sidewall) or a failure from overheating (low pressure) or normal use. If recently purchased, a tire company might inspect and compensate or inspect and not, whether under warranty or not.

Unless you're into tire forensics or you claim firm cause and effect, the tire manufacturer usually makes the call.

Sherwood

T77911S · 11-05-2019, 03:09 AM

well just did another track day at NCM in Kentucky.
tires did fine. or should say not torn up like last time,.
was running much lower pressure this time, around 38psi gave me pretty even temps but only checked the front.
last time my tire temps went up over 10 degrees to 46 on the first session.

the track was in really bad shape at the first one so I may have to credit it to that.

I do have another question about my brothers tires.
he has a Z4 M, -3 camber up front, stffer springs but he is wearing out the very outside edge of his tires. the rest of the tire looks new when the outside is getting worn down to the cords.
any ideas.