Myth or true - Wider tyres less likely to Glass puncture - but more likely to pinch puncture?

[RideToWorky]

Hi All,

Myth or true - Wider tyres less likely to Nail puncture - but more likely to pinch puncture?


Nail puncture:
Wider tyre has larger contact surface to road.
when run over glass/nail etc - there is LESS PRESSURE - as larger surface to take hit? (Larger the surface, the lower the pressure?!)
Thus - less likely for nail to penetrate as deep?! THus less likely to have a puncture.
Is there anything in this wacky physics interpretation!


Pinch Puncture:
Wider tyres / Lower pressures - more floppy rubber to have a pinch puncture situation?!


Hope you can advise

Regards
Martin

[irc]

Hi All,

Myth or true - Wider tyres less likely to Nail puncture - but more likely to pinch puncture?


Pinch Puncture:
Wider tyres / Lower pressures - more floppy rubber to have a pinch puncture situation?!

Not true. Wider tyres are at lower pressure but as they are wider the drop should be similar to narrow tyres. IE when the rider mounts the bike the amount the tyre deforms should be roughly the same. 15% for example.

So a rider on 700x25s at 110psi or 700x32s at 70psi will both have around 15% tyre drop and should have the same low chance of pinch flats. Either could pinch flat if running under inflated tyres.

http://www.bikequarterly.com/images/TireDrop.pdf


As for punctures? No idea. The pressure theory makes sense but is it balanced out by the fact wider tyres are going to run over more nails because they will hit some a narrower tyre would have missed.

[DaveP]

Oh if that nail has your number on it the type of tyre is immaterial
Agree about pinch punctures. Wide and narrow tyres, appropriately inflated, ought to have comparable resistance to this.
As for foreign body punctures, there is a school of thought that says that harder tyres ought to be more resistant, because softer tyres flex more, which can help anything that manages to attach itself to work its way deeper. With a hard tyre things effectively "bounce off".
Although I think I understand the argument, I don't think I've ever been totally convinced by it. My impression is that my punctures seem to have more to do with where I'm riding than what I'm riding on. And there is such a wide range of tyre structures available today that generalisation is difficult.

Pack a puncture kit. Enjoy your ride, and if she who must never be named favours you with her attentions console yourself with the thought that you probably won't get another - until you've put everything away

[Vorpal]

I think that wider tyres are less prone to pinch puncture. A 23 mm tyre has to be kept religiously up to pressure, or you will experience a pinch puncture. Unless it is already very low, a wider tyre can lose quite a lot of air before a pinch puncture is a risk.

[SpannerGeek]

I run 25mm tyres on my summer bike, I can run them at fairly low pressure (60psi) msinly for comfort and have only experienced one pinch puncture which to be honest would have happened with any tyre. With 23mm and less they really need to be rock hard ime.