Conti Tyre Blowout

I blew out the sidewall in my back tyre while touring a couple of days
ago. It was a Conti TT 2000 700x37 on a Mavic T224 rim. The tyre
concerned had about 2000 miles on it and failed right at the rim. It
was inflated to 80psi against a rec max of 70psi. The tread was worn
but nowhere near threadbare.
Of more concern was the fact when I checked the front tyre ( 700x32
same mileage but plenty tread left) I found extensive wear at the same
area all round the rim.
Searching previous threads on this group it seems Contis are prone
to sidewall failure. Espescially with some Mavic rims.
So both tyres ditched. I'm tending towards 700x32 Schwalbe
Marathons to replace the Contis.
Anyone know any good deals on Marathons just now or going to
persuade me to get anything else.
Iain

wrote:
It was inflated to 80psi against a rec max of 70psi.

And you're still wondering why it failed? You did well to get 2,000 miles
out of it under that pressure.


Pete.

PeteC wrote:

And you're still wondering why it failed? You did well to get 2,000 miles
out of it under that pressure.


Pete.




I wouldn't argue the fact, but I'm having damn trouble believing that
would make much difference.

--
Mark
_____________________________________________

Deja Moo - The feeling that you've heard this bull before

PeteC wrote:
wrote:
It was inflated to 80psi against a rec max of 70psi.

And you're still wondering why it failed? You did well to get 2,000 miles
out of it under that pressure.

Fair enough I was over the max pressure on the back. As I weigh about
215 pounds and was carrying 30 pounds in rear panniers I felt 80psi
wasn't excessive. Sheldon Brown states in his article on tyres
pressures when referring to manufacturers values

" These values are only very approximate, and experienced cyclists will
rarely pay much attention to the rated pressure."

Also the front tyre was inflated to 65 psi as it was carrying a lesser
load. The tread on it was showing very little wear but as I said it
also showed excessive sidewall wear. So I don't think high pressure was
the primary cause.
2000 touring miles on a tyre for a heavy rider is reasonable and I
would not call it premature failure. I thought it worth flagging up
this failure as it will certainly prompt me to have closer inspections
of my tyres every now and again.
Iain

PeteC wrote:

wrote:

It was inflated to 80psi against a rec max of 70psi.


And you're still wondering why it failed? You did well to get 2,000 miles
out of it under that pressure.


Nonsense. Most tyres (well, all tyres that I have ever used) perform
perfectly well at substantially over the rated pressure. It is standard
operating practice for tandemers, where the loads are much higher than
for single cyclists.

Yes, contis sometimes fail at that point. I thought this was an old
problem now solved, but I don't use them. It might be worth checking
that the chafing strip is properly positioned.

James

wrote:
I blew out the sidewall in my back tyre while touring a couple of days
ago. It was a Conti TT 2000 700x37 on a Mavic T224 rim. The tyre
concerned had about 2000 miles on it and failed right at the rim. It
was inflated to 80psi against a rec max of 70psi. The tread was worn
but nowhere near threadbare.
Of more concern was the fact when I checked the front tyre ( 700x32
same mileage but plenty tread left) I found extensive wear at the same
area all round the rim.
Searching previous threads on this group it seems Contis are prone
to sidewall failure. Espescially with some Mavic rims.

This is a particular issue with using wide tyres on narrow ryms. It is
not related to overinflation, indeed, if anything it's related to
underinflation.

What happens is that where the tyre sydewall bulges outward over the
top of the rym, it rubs and abrades. This motion and abrasion is
greater with lower pressures.

37 mm tyres of any brand are going to be a bit wyde for that particular
rym.

Unfortunately, using pressure high enough to prevent this will
generally defeat the purpose of the wyde tyres.

Sheldon "Note Brytish Spelling!" Brown
Newtonville, Massachusetts
+--------------------------------------------+
| If you haven't yet discovered the novels |
| of Neal Stephenson, don't wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

wrote:
I blew out the sidewall in my back tyre while touring a couple of days
ago. It was a Conti TT 2000 700x37 on a Mavic T224 rim. The tyre
concerned had about 2000 miles on it and failed right at the rim. It
was inflated to 80psi against a rec max of 70psi. The tread was worn
but nowhere near threadbare.
Of more concern was the fact when I checked the front tyre ( 700x32
same mileage but plenty tread left) I found extensive wear at the same
area all round the rim.
Searching previous threads on this group it seems Contis are prone
to sidewall failure. Espescially with some Mavic rims.

This is a particular issue with using wide tyres on narrow ryms. It is
not related to overinflation, indeed, if anything it's related to
underinflation.

What happens is that where the tyre sydewall bulges outward over the
top of the rym, it rubs and abrades. This motion and abrasion is
greater with lower pressures.

37 mm tyres of any brand are going to be a bit wyde for that particular
rym.

Unfortunately, using pressure high enough to prevent this will
generally defeat the purpose of the wyde tyres.

Sheldon "Note Brytish Spelling!" Brown
Newtonville, Massachusetts
+--------------------------------------------+
| If you haven't yet discovered the novels |
| of Neal Stephenson, don't wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

wrote in message
oups.com...

Sheldon "Note Brytish Spelling!" Brown
Newtonville, Massachusetts

Indeed Sheldon is so proud of his correct spelling, that he posted twice ;-)

Cor Blimey! helen s

in message .com,
') wrote:

Unfortunately, using pressure high enough to prevent this will
generally defeat the purpose of the wyde tyres.

Sheldon "Note Brytish Spelling!" Brown
Newtonville, Massachusetts

You mipsellsed 'thys' and aslo 'wyll'. HTH. HNAD.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
;; This email may contain confidential or otherwise privileged
;; information, though, quite frankly, if you're not the intended
;; recipient and you've got nothing better to do than read other
;; folks' emails then I'm glad to have brightened up your sad little
;; life a tiny bit.

Just in case anybody is interested - I just noticed that my Schwalbe
marathon rear tyre has worn nearly smooth and has done about 6000 km
(including LEJOG and other heavy loaded cycle camping, lotsa roughish
trail rides etc). Front tyre looks good for another 3000km.
No punctures at all so far.
700x32 on Mavic T224 on Dawes Galaxy.