Pinch Flats due to worn tyre?

daxplusplus

I wouldn't have thought that having a worn tyre would contribute to pinch flats but is it possible that it does?

I've probably just been unlucky - none for a couple of thousand of miles and now two within a few hundred. Also the first one I can understand .. the road surface was atrocious .. but todays was a bit of a mystery, no obvious event that caused it.

Is it more likely there is something wrong with wheel (I'll check tonight when I get home whether todays pinch flat is in exactly the same spot as the previous one but I don't think it is)

Just wondering what other peoples thoughts are.

andy_wrx

You get a 'classic' pinch flat when the tyre is squashed flat, e.g by riding over sharp edge of a pothole, so that the tyre is squashed flat against the wheelrim, trapping the tube between the two.
Thus you get them by having low pressure in the tube, allowing the tyre to be squashed flat, where if it were properly inflated it wouldn't have.

Now if the sidewall is damaged, that could have same effect.

But if by worn you mean the centre of the tread is worn-down and thinner, then that would allow more penetrating-object type punctures as the tread is thinner, but not snakebites.

Dave_P1

What pressure do you run the tyres at?

daxplusplus

Thanks for the replies.

The previous pinch flat was in a completely different part of the tube so it's not a wheel thing (phew).

I run 700 x 23 at approx 110 both front and back. Top them up every couple of weeks (attach the pump, let a load of air out as I do, pump them back up to 110).

The tyre has worn normally over approx 1500 miles - just main part of the tread squaring off .. I never realised they did that in quite such a pronounced manner - just like a motobike tyre - not surprising really as they are the same thing :-) Can't say I've noticed it affecting handling like it does on a motorbike though.

ilm_zero7

try 120 psi- minimum, but much depends on your weight

rolf_f

DaxPlusPlus wrote:

I run 700 x 23 at approx 110 both front and back. Top them up every couple of weeks (attach the pump, let a load of air out as I do, pump them back up to 110).

Why do you let the air out? It doesn't go off

110 seems plenty. Are you very heavy (impolite question but needs asking!)?

Hoopdriver

110psi is plenty. There is no need to go any higher. In fact, it is counter-productive unless you are riding on glassy smooth tracks, as the R&D departments of most tyre manufacturers will tell you.

alpineaddict

DaxPlusPlus wrote:

I wouldn't have thought that having a worn tyre would contribute to pinch flats but is it possible that it does?

I've probably just been unlucky - none for a couple of thousand of miles and now two within a few hundred. Also the first one I can understand .. the road surface was atrocious .. but todays was a bit of a mystery, no obvious event that caused it.

Is it more likely there is something wrong with wheel (I'll check tonight when I get home whether todays pinch flat is in exactly the same spot as the previous one but I don't think it is)

Just wondering what other peoples thoughts are.

Similar thing for me today... Not had a single puncture in about 18 months of 'on/off'' cycling, and I get one today 4 miles from where I left my car... Put a new tube in and got a second puncture form pinching the tube (I think) when I put it back on, so put another tube on and that had a hole in it :x :x :x :x 3 tubes down my mate went for the car and came back for me... Quick Q, at what point do you dicide the small slit in the tyre is worthy of you getting a new tyre?

fwiw I have my tyres to around 120 psi...

daxplusplus

Rolf F wrote:

Are you very heavy (impolite question but needs asking!)?

85kg last time I looked .. so I think enough weight to easily cause a pinch flat if I'm a bit ham fisted with the bike but not a weight that's going to cause an usually high incidence of them.

Herbsman

I totally forgot about this but try covering your tubes in powdered chalk or talcum powder to reduce friction between tyre and tube. This stopped me getting pinch flats on my BMX years ago (when you accidentally hit your back wheel on the edge of a quarterpipe from 6ft in the air). May help prevent pinch flats on a road bike.

This article - http://www.sheldonbrown.com/brandt/talcum.html - says it doesn't work and that it's an urban myth, but my tubes never blew up after I started using it.

George at G-Sport says chalk + wider rims works. http://www.gsportbmx.co.uk/support/ride ... tures.html