View Full Version : BFG G-Force Sport Warning - Tread Separation
If you are running the older versions of these be on the lookout for tread separation.
These are the old ones (not the new Comp 2s)
We had a Tread Separation at Big Bend Open Road Race going south and apparently ran another 105+ miles averaging 140.00 MPH with 20% of the tread on the inside of a back tire missing. On our in car video, about 12 miles in on our south run, there is a little noise and vibration that smooths out after 2-3 seconds that has to be the tire coming apart. We thought it was just a washboard patch in the road at the time.
https://static1.pt-content.com/images/pt/2012/05/dscn0271-1.jpg
https://static1.pt-content.com/images/pt/2012/05/dscn0276-1.jpg
Because it was the inside back of a low car, it wasn't until we changed the oil that we noticed it.
The Tires were 3 years old and were always used in back and have never touched metal. Someone told me they had two separate tread separations with different sizes of this tire, two weeks later, we had one, too.
These Tires are W rated but appear to have design or manufacturing flaw.
If it was a front tire that let go, It might have been my driving or fender rub, but a back tire, furthest away from the fender has to be the tire.
Mr Nick
05-12-2012, 06:31 AM
That could have ended much worse!
Have you contacted BFG (MAST) to get their opinion of this? They may even request to see the tire.
SLO_Z28
05-12-2012, 09:55 AM
Can you post a picture of the date code of the tire for me?
TheJDMan
05-12-2012, 10:40 AM
That's one of those kind of things that scares the hell out of you the more you think about it.
Thanks for the input. The tires are down in the storage garage. I'll post pictures of the date codes tomorrow.
Here is video of the only time during the 118 mile run the tread could have come off, just over 11 miles from the start. The Rally computer says we had averaged over 154 mph for those 11 miles.
VATOAgG08b8
Vegas69
05-13-2012, 08:27 PM
Your first mistake was running those speeds for that long on old tires. I'm really surprised they didn't require you to have new or really close to new tires.
DTM Racing
05-14-2012, 05:42 AM
Your first mistake was running those speeds for that long on old tires. I'm really surprised they didn't require you to have new or really close to new tires.
Running at anything over 100mph constantly on anything less than an R-Comp is a big no-no.
Thant being said, even the KDW has this same problem I can show you plenty of brand new KDW's that are corded on the outside. Just poor design.
Your first mistake was running those speeds for that long on old tires. I'm really surprised they didn't require you to have new or really close to new tires.
We are going to check the Date codes, but the tires shouldn't be older than 2009 with less than 2000 miles on them. Every 2009 ZR1 or 2008 Z06 in the race had older tires. The Tires were either Purchased January 2009 or June 2009.
We do swap out tires every 3 years, even if they don't need it and this was this set's last race or they had one more, slower speed race before they were retired.
These are W rated (168 mph) tires.
If a tires speed rating is only valid for 2 years (or 2 months), they should say that.
Running at anything over 100mph constantly on anything less than an R-Comp is a big no-no.
These are W rated tires. They must not sell any in Europe because I've had my rental Diesel minivans above 100 mph for extended periods of time there, I was getting passed by every crap box on the road.
DTM Racing
05-14-2012, 12:37 PM
These are W rated tires. They must not sell any in Europe because I've had my rental Diesel minivans above 100 mph for extended periods of time there, I was getting passed by every crap box on the road.
I've had one street tire completely delaminate on me at speed before, and it was very similar to what you guys experienced, except with a huge BAM! after the vibrations, when a major portion of the tire came up into the fender. When we pulled over the entire tread portion of the tire had come off of the front drivers side. That plus enough videos of people tires coming apart and destroying the car, and I'll stick to fresh race tires for high speed events. Better to be a few bucks poorer than dead.
I've had one street tire completely delaminate on me at speed before, and it was very similar to what you guys experienced, except with a huge BAM! after the vibrations, when a major portion of the tire came up into the fender. When we pulled over the entire tread portion of the tire had come off of the front drivers side. That plus enough videos of people tires coming apart and destroying the car, and I'll stick to fresh race tires for high speed events. Better to be a few bucks poorer than dead.
But how fresh is Fresh?
We bought the tire from Tire Rack in July 2009... That's newer than the tires on Every 2009 model car and many 2010 Camaros.
Other than being asked to go 167 mph in a straight line for 50 miles once a year for 2 years, the tire that came apart has had a pretty easy life. It has never been on the front of the car, It sits in a garage off the car 9 months out of the year, and the max lateral G force it has ever endured is maybe .90g for a few seconds... and the INSIDE shoulder came apart.
I totally agree thart Fresh tires are ideal, but this is pointing more to a defective tire.
Vegas69
05-14-2012, 03:35 PM
I can't find anything definitive but the speed rating is not for the duration in your application. Age is a huge factor with tires. I'm pretty sure they require brand new tires in the Silver State classic for this exact reason. With anything in racing, always leave yourself a cushion. Glad it didn't turn really really ugly for you.
toploader
05-14-2012, 05:44 PM
WOW, i never was a BF fan, i just picked up some Michelin Pilot Super Sports and ive trusted Michelins for years on the track.
I can't find anything definitive but the speed rating is not for the duration in your application. Age is a huge factor with tires. I'm pretty sure they require brand new tires in the Silver State classic for this exact reason. With anything in racing, always leave yourself a cushion. Glad it didn't turn really really ugly for you.
The Speed rating is supposed to be for 30 minutes at the speed rating at 85% of the max load on the sidewall with no damage done to the tire.
We were 500lbs+ light and 25 minutes short of the speed rating before the tire gave out. 25 minutes is a pretty big cushion.
The rules at the Silverstate are "should not be over 2 Years old" which is kind of squishy. These tires were 2 years and 9 months old and the defective one failed after 4.5 minutes.
A week before the BBORR a guy on Turbobuick.com posted that he had two different sets of BFG G-Forces Sports have the tread separate:
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
https://static1.pt-content.com/images/noimg.gif
At the time, I told him "We've never had a problem with ours".
Now I'm sensing a pattern.
Needless to say, if you are using still using BFG G-force Sports for ANY high performance car fun, stop immeadiately, send them to the recycler and buy some new tires... even if they are "2 years old" and have less than 1000 miles on them.
JEFFTATE
05-15-2012, 05:21 AM
What was the date code on the tire ?
You may have bought them 2 yrs and 9 months ago , but they may be 3 or 3 1/2 years old ..
I wouldn't punish any tire over 2 yrs old .
My feeling is , this isn't a BFG problem , it's an age problem .
Here's how to find and determine it .
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=11
AJ_McPherson
10-01-2012, 09:43 AM
What kind of tire pressure were you running in these? Typically 2 things cause (new) tires to fail in this way. Temperature (too hot) and pressure (too low).. My initial guess would be the pressure is too low. you must follow the guidelines listed here.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=72
Basically when pressure is low it causes excessive movement in the shoulder area of the tire building heat at high speeds. This causes the tread to separate like you have showing.
Also Tire Age does has a lot to do with it. When you Compress air it produces Water vapor. This water vapor can penetrate the rubber of the tire and make its way to the steal belts and cause them to rust. This just attacks the integrity of the tire. Ideally running Nitrogen would be a better option for a racing situation like this.
Also when Rubber gets old it becomes brittle. Its fairly pliable when its new but after 2+ year it can become brittle and start to crack. This cracking can propagate and cause a failure.
The tire had 34 psi cold in it. It wasn't overload/overheat failure because the tire that failed was the lightest loaded shoulder on the the lightest loaded tire (inside shoulder of back tire, with 1.5" between tire & frame). I put my hand on the front tire after every run and they are warm, but not "hot".
It wasn't a "rust" issue from water vapor, because the tire still held air and Averaged 140 mph for another 110 miles after the tread separated. The Internal air had no contact with the area of the tread that failed.
The tires were only on the car only a couple times a year... the rest of the time it sits on "Garage tires" to avoid flat spotting, so other than asking them to go 168 mph twice a year, they have a pretty easy life.
It was either an age issue or tire defect. the failed Tire was 3 years old with less than 1000 miles on it.
This is a good lesson to anyone who wants to enter an open road race with a 2010 or older "new" car that still has the original tires one it.
Powered by vBulletin®