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Old 12-11-2012, 06:32 PM
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Quote:
Originally Posted by TXFred View Post
I'm going to take issue with this, based on my expertise.

My qualifications:
1. I think I know what I'm talking about.

I've had the distinct pleasure of destroying a run-flat tire. This was less than a week after I got my 335i. I had a nail in the right rear, and before I could get it repaired, I had an emergency. As a result of this, I had to drive 7 miles at about 90mph, on a flat run-flat.

(In hindsight, I should have taken two minutes to fire up the air compressor and re-inflate the tire. But bad things were happening, and I was panicked.)

Later, I took the car in to Discount Tire to have it patched, and the damage was very obvious. The inside of the tire was filled with what looked like black ball bearings. These were composed of rubber dust that had reformed into little balls as the tire rotated. The inside of the sidewalls was visibly damaged, with a crack running the entire way around each sidewall. This was the source of the dust.

From the outside, the tire looked just fine.

Seeing the damage, Discount Tire quite correctly refused to re-mount the tire. I bought a new one.

The point of this is, if you drive on your run-flat fast enough or long enough to damage it, the damage will be obvious when the tire is dismounted for repair.

Frederic
TXFred,

Well stated.
There CERTAINLY is a way for a professional tire shop to determine if a tire has been damaged beyond the repair limit as you've pointed out. IT MUST BE DISMOUNTED and inspected. THIS is exactly the problem with "plug" repairs. All tires have a thin layer (about 1mm) of butyl rubber...the "inner liner" on the interior of the tire...the critical defense against air leakage. If this gets damaged from underinflation, the integrity of whole tire is compromised, consequently the necessity to inspect the interior of the tire.
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