I had recently changed my rear tire after a 7,000 mile cross country tour with friends from the East coast to the West coast and back. The tire had 8,039 miles prior to my departure and looked in great shape. During the ride out we had noticed the rear tire starting to cup. The next morning with cold tires I checked the pressure and found it to be at the recommend pressure of 48 PSI. Concerned about the cupping I kept a close watch on the tire and pressure. On the way back about 1500 miles from home I noticed a roughness in the bike when coming to a stop. Inspection again revealed the cupping getting worst. Prior to my last fuel stop arriving home the cupping was severe. With 200 miles to go and a little care I figured I could make it safely home. I am very religious about my tire pressures and use an Accugauge tire gauge to insure accurate pressures. This was my first Bridgestone after running two sets of Metzler’s on the LT with no problems. By the time I arrived home it was very prevalent that something was seriously wrong. After removing the tire I decided to section the tire. Examination of the tire revealed the tire had separated on both sides of center. On the swing-arm side it started rubbing the swing-arm to the point it left a .040 thousands wear notch. This happened sometime during the last 200 miles of the trip. In the images of the tire cross-section you can see the severity of the separations. Separation was found in all seven sections of the tire. Also notice the one hundred sixty thousands clearance between the swing arm and a newly install Metzler. This is a little closer than I expected for swing-arm to tire clearance.
Because it is only a sample of one of this tire and I do not know the makings of the Bridgestone motorcycle tires, I can not conclude a definitive failure analysis. But I do know the history of the tire and compared to the Metzler’s I have run on this bike in the past this has never happened. As a failure analysis technician at Lockheed Martin my knowledge and background tells me this tire was defective from the beginning and perpetuated over time. My thinking is, if a tire is kept to proper inflation and not abused/overloaded you should be able to run a tire to the cords without having this type of failure. After arriving home I compared the Accugauge tire pressure gauge to another gauge to find it was reading were correct. I consider myself lucky the tire did not totally fail riding two up at highway speeds pulling a trailer.
Is this the famous Firestone separation failure problem?
Below is the history of the tire.
Tire: Bridgestone BT020R 160/70R-17
Motorcycle: 2001 BMW K1200LT
Installed date and mileage: October 2, 12003 @ 20,008 miles
Removed date and mileage: September 26, 2005 @ 35,022 miles
Total mileage: 15,014
Tired pressure: 48 PSI cold
Ride loads: One up 10%, Two up 40%, Two up with Un-igo 35%, One up with Un-igo 15%
Rider/SO weight: 159Lbs. / 140Lbs.
Trailer: Uni-go
Links:
Bridgestone BT020R 160/70R-17 tire failure web page.
http://pulsefl.0catch.com/bt020r/
Word document:
http://pulsefl.0catch.com/bt020r/Bridgestone_tire_failure.doc
Individual images links:
http://pulsefl.0catch.com/bt020r/tire-1.jpg
http://pulsefl.0catch.com/bt020r/tire-2.jpg
http://pulsefl.0catch.com/bt020r/tire-3.jpg
http://pulsefl.0catch.com/bt020r/sections.jpg
http://pulsefl.0catch.com/bt020r/section_a-1.jpg
http://pulsefl.0catch.com/bt020r/section_a-2.jpg
http://pulsefl.0catch.com/bt020r/section_a-3.jpg
http://pulsefl.0catch.com/bt020r/section_b-1.jpg
http://pulsefl.0catch.com/bt020r/section_b-2.jpg
http://pulsefl.0catch.com/bt020r/section_b-3.jpg
http://pulsefl.0catch.com/bt020r/section_c-1.jpg
http://pulsefl.0catch.com/bt020r/swingarm-1.jpg
http://pulsefl.0catch.com/bt020r/swingarm-2.jpg
http://pulsefl.0catch.com/bt020r/swingarm-3.jpg
http://pulsefl.0catch.com/bt020r/swingarm-4.jpg
http://pulsefl.0catch.com/bt020r/new_install.jpg
Because it is only a sample of one of this tire and I do not know the makings of the Bridgestone motorcycle tires, I can not conclude a definitive failure analysis. But I do know the history of the tire and compared to the Metzler’s I have run on this bike in the past this has never happened. As a failure analysis technician at Lockheed Martin my knowledge and background tells me this tire was defective from the beginning and perpetuated over time. My thinking is, if a tire is kept to proper inflation and not abused/overloaded you should be able to run a tire to the cords without having this type of failure. After arriving home I compared the Accugauge tire pressure gauge to another gauge to find it was reading were correct. I consider myself lucky the tire did not totally fail riding two up at highway speeds pulling a trailer.
Is this the famous Firestone separation failure problem?
Below is the history of the tire.
Tire: Bridgestone BT020R 160/70R-17
Motorcycle: 2001 BMW K1200LT
Installed date and mileage: October 2, 12003 @ 20,008 miles
Removed date and mileage: September 26, 2005 @ 35,022 miles
Total mileage: 15,014
Tired pressure: 48 PSI cold
Ride loads: One up 10%, Two up 40%, Two up with Un-igo 35%, One up with Un-igo 15%
Rider/SO weight: 159Lbs. / 140Lbs.
Trailer: Uni-go
Links:
Bridgestone BT020R 160/70R-17 tire failure web page.
http://pulsefl.0catch.com/bt020r/
Word document:
http://pulsefl.0catch.com/bt020r/Bridgestone_tire_failure.doc
Individual images links:
http://pulsefl.0catch.com/bt020r/tire-1.jpg
http://pulsefl.0catch.com/bt020r/tire-2.jpg
http://pulsefl.0catch.com/bt020r/tire-3.jpg
http://pulsefl.0catch.com/bt020r/sections.jpg
http://pulsefl.0catch.com/bt020r/section_a-1.jpg
http://pulsefl.0catch.com/bt020r/section_a-2.jpg
http://pulsefl.0catch.com/bt020r/section_a-3.jpg
http://pulsefl.0catch.com/bt020r/section_b-1.jpg
http://pulsefl.0catch.com/bt020r/section_b-2.jpg
http://pulsefl.0catch.com/bt020r/section_b-3.jpg
http://pulsefl.0catch.com/bt020r/section_c-1.jpg
http://pulsefl.0catch.com/bt020r/swingarm-1.jpg
http://pulsefl.0catch.com/bt020r/swingarm-2.jpg
http://pulsefl.0catch.com/bt020r/swingarm-3.jpg
http://pulsefl.0catch.com/bt020r/swingarm-4.jpg
http://pulsefl.0catch.com/bt020r/new_install.jpg
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