conti 4000 sidewall crack

le_boss

Bought a pair of conti 4000 about 6 weeks ago (was fed up of punctures) and they have been brilliant. however, i have only done about 1000miles on them and i notice that the front has a crack all the way around the tyre right on the sidewall. just wondering if i should change the tyres? i mean is this dangerous? will it suddenly collapse?

is this common with contis?

are there any tyres out there with the same puncture resistance as contis but without being prone to this sidewall cracks??

thanks for any help

sungod

never had this with my gp4000s ones, never seen any similar posting about conti tyres, sounds very unusual

how deep is the crack? is the sidewall coloured? if so it might just be cosmetic

a tyre on too narrow a rim, or really underinflated might suffer from the extra stress, but to happen in 6 weeks it'd need to have been a long way out

assuming they're 23mm if you've got them inflated to around 100psi then if there was a serious crack/cut the tyre would be bulging out due to the pressure, if there's no distortion then probably it's ok

if you are worried, take it back to the shop, or contact the seller if it was bought online

le_boss

thanks for your advice.

there is no sign of the tube but the crack goes all the way around. just noticed its the same on the rear as well.

they are 23mm and always keep them at about 100-110 (depends on weather). had them at 110 today. but to be honest im not sure when the crack appeared. was just giving the bike a good wash and noticed it.

at over £30 each, this isnt something i was expecting!

i will try and upload a photo of it....if i can figure out how to upload a picture!

le_boss

heres a couple of photos of it

http://picasaweb.google.com/11251447179 ... 8800521234

its like this on both sides all the way around (both tyres)

sungod

you mean the radial mark through the last 0 in 4000?

that's just a moulding mark not a crack, same on all mine, not a problem

btw i assumed you meant a crack around the circumference of the tyre, or am i missing it in the picture?

topdude

Is your crack (pardon me) all round the tyre about 5mm from the rim, can't realy see in your photos?
If so it is the same on mine, looks like a slight de-lamination of the carcase near the bead ?
It has never caused any problem so i just ignore it

le_boss

hi

yes it is approx 5mm from the rim.
ive just spent the last hour looking at it and it doesnt seem too deep, almost like its an outer layer???

doesnt seem to have gone all the way through (seems ok on inside of the tyre.

just a bit concerned that the sidewall may collapse or something as im riding??

thanks for your help

sungod

the bit of the tyre nearest the rim is much thinner, just rubber covering the underlying plies that are what actually give the strength, then extra rubber for the contact surface goes on top

what you are seeing is just the point where this top layer ends, the lower layer is continuous around the tyre, there's no crack

you can see how it's constructed in this diagram...

http://www.conti-online.com/generator/w ... 00_en.html

bexley5200

they have to join the tyre somewhere

marin_maniac

Don't worry about it. I had this on some GP4000s and the Ultra Sport's that came with my current bike.

le_boss

thanks for the help guys.

wont worry too much about it now.

out of interest, any idea how long these tyres last? (how many miles)
i know they have the indicator, but just wondering roughly.

thanks again

sungod

depends on the surface and how lucky you are

the rear will wear much faster than the front, but they'll last many thousands of miles, barring cuts i'd guess 10k for the rear

the only reason i've ever changed a gp4000s is bad cuts - where the tyre was bulging, or the breaker had a cut >5mm in it, sadly this has been long before wear was an issue

kettrinboy

my oldest GP4000S pair have done 8000 miles and the wear dimples are still visible, some people would change them well before that but mine are working fine so i,ll use them until the wear indicators disappear which will be another 500-1000miles approx

fnegroni

GP4000S here:

Just had two punctures on the same tyre within 200miles of each other, when the tyre had about 2k miles. No punctures up to now in 9 months of riding those tyres. The first pucture happened when the tyre was mounted on the rear, on an uphill.
The second puncture today after I decided to put in in the front, after a couple of miles of 'white' road.
I just ordered a new GP4000S to replace the one subject to punctures.
The wear dots are visible but less than half a millimeter left. A very noticeable step between unworn side and worn side is also visible.

I reckon if I swapped the front and rear tyres again, the total life of one tyre (first mounted at front and then at rear) would be around 3.5k miles.
All of this is very much dependent on your weight, weight distribution, how hard you ride, and road surface.
I average about 18mph on 50 to 100 mile rides, weigh 72 kg and like climbing but mostly is ondulations in the south east of England.

The tyres I had previously had no punctures but the same wear level was noticed after only 1,000 miles, which means the compound on the gp4000s is certainly more durable.