I would welcome knowledgeable answers rather than opinions please. I have been cycling 50+ years and now work in an LBS.
I have seen numerous examples of so-called “thorn-proof” TP tubes, of different makes, on customers’ bikes, where the Schrader valve stem has ripped out from the tube. This is particularly so with wider tyres, like 48 mm and up.
Initially we put it down to people using a slightly under-width tube due to what being all that was readily available, and also under inflation. However, even with TP tubes that are bang on the numbers, and inflated close to the max. recommended pressure, we see a common excessive failure rate where the valve stem parts from the tube, sometimes repeatedly, where the standard tubes do not fail this way. Customers request TP because we are prone to goathead thorns (aka bindi, doublegee etc.) around here.
The thick rubber TP tubes are clearly less stretchy than thinner tubes, and thus possibly more prone to tearing.
Does anyone have any real factual technical insight into what I’m describing? Many thanks.