1 Apr 2016

1st April 2016 [II] Tyres"R"[NOT]Us!


I have been putting off replacing the Durano tyres despite having a set of Durano Plus waiting for months now in their sales-presentation boxes. The Duranos had been showing small cuts and holes for ages but seemed to be surviving well into old age. The first puncture this year may say more about my low mileages than sheer tyre longevity. Only 1300 miles covered since the last puncture.

From my mileage diary I found I had fitted the new Duranos at the end of August for a total mileage of 2627 to date. Which doesn't seem much by Durano standards. Though the tyre treads on trikes don't enjoy any roll on corners [like bikes] so tend to flatten more quickly on the crowns. Inflating them to a pressure of 90-95psi probably tends to wear the crown away even faster. The thinner crown lifts in contact with the rough road and is then worn away. Though it is possible the reinforcing fabric prevents this from happening. Riding over wet/dry roads leaves a stripe showing that the contact patch is only about 1cm wide before the tyres have warmed up. This widens after a few miles.

Once I had removed the worn tyre I immediately noticed how light and thin the tread felt compared to new. New tyres have a full, thick crescent of rubber covering the entire tread. A worn tyre from thousands of miles on a trike is both thin and has no extra thickness over the crown. Though I was surprised when I just checked with a dial equipped, thickness gauge and found there is still 3mm of rubber left on the middle of the tread. It certainly doesn't feel that thick to the bare fingers.The worn tyres weighed 1/2 lb or 8oz each. The brand new Durano Plus have a tread thickness of 5mm.

Now I am wondering whether it is worth the risk of further punctures by just replacing the inner tube. Or going the whole hog and replacing all three tubes and tyres with the new ones. The inner tube which rolled home without air obviously has to go. It was gathered into a bundle around the valve and must have been battered quite hard. Though the anodized, rim finish is completely untouched by rolling on the flat tyre. The puncture was tiny and took two tries through the water before it finally showed up.

A puncture is a real nuisance, particularly in the wet when everything is covered in sticky, road silt. It is impossible to clean one's hands, or the tyre, of fine grit beside the road. Fitting even the undersized patches they sell for narrow inner tubes is usually a waste of time. The curvature of the 20-25mm inner tubes is far too small to wrap the patch properly and eventually it just lifts off again. I once tried a G-cramp [C-clamp] to press a patch into place but it didn't help. Inner tubes often have raised ribs which would seem to negate any chance of a patch fitting closely by thumb pressure alone.

Even having to stop to put a new inner tube into a punctured tyre, while out on the road, adds to the journey time. Try it in the dark! The tyre has to be carefully checked all around for the tiny flint which had caused the puncture in the first place. So, I had better stop messing about and fit the new tyres and tubes so I can start from scratch with the lowest possible risk of a puncture. With the highest mileage months ahead it seems false optimism to continue on the old tyres. 

If only life were perfect. I was just finishing my last tyre change and congratulating myself on my finely honed skills. Then I discovered that Schwalbe tubes cannot be trusted for air-tightness. A leak on the inner side of the tube, close to the valve, would be impossible to achieve given my usual care in fitting. Had the leak been opposite the valve I might have thought there was a very slight chance I had trapped the tube getting the last bit of tyre bead over the rim. Though I always put a little air in the tube to minimize this risk. Nor do I ever use tyre levers to fit the tyre. That would be asking for trouble. I always put a few strokes more air in the fitted tyre and go right around pressing the bead away the from the rim to ensure the inner tube isn't trapped anywhere. Then add even more air and pull the bead line up to the rim. Both sides get exactly the same treatment, of course, starting at the valve to avoid missing anything.

I haven't had a tyre with a new inner tube go down on me due to a self-imposed puncture during fitting in living memory. So how does a tube puncture close to the valve on the inside facing the rim? I have absolutely no idea. I had to pull the new tube out and fit one of the old tubes in its place and this is happily holding its pressure. I even double checked that I had 90psi using the digital pressure gauge to ensure my track pump gauge wasn't becoming inaccurate and under-reading. Both gauges agreed.

A leaky, brand new inner tube is a very serious matter. It could actually mean life or death under the wrong circumstances. I know I shall never trust new inner tubes ever again without test inflating them first and checking in a clean water bath. It's just not worth the risk! Schwalbe claim they test for leaks before sale. I think they [probably] mean they only test random samples to save expense. Perhaps they have unhappy workers in Indonesia? What do I know? Except that I have a leak in a brand new, Schwalbe inner tube.

Just in case Schwalbe is remotely interested the image shows the batch number of the leaking tube. It is otherwise marked Schwalbe 700x20-28C No15.  I suggest my readers check your own stock inner tubes for air tightness before assuming you can carry them safely in your saddlebag ready for use in an emergency. Mine have never left the smart boxes they came in from the online dealer until I opened them today. I didn't even put them on the clean concrete slabs but rested them carefully on the tyres for the posed picture above.

I have had Continental inner tubes with faulty valves which would never hold air [at all] however they were adjusted! Others, by the same manufacturer, where the valves hadn't been tightened into the valve body. So that the whole valve came out when unscrewing the active 'pip' just to put air in the brand new inner tube! So this is obviously a quality control problem during manufacture which regularly slips through. I had three in a row like that!

Can you imagine puncturing a very long way from home when you are already tired? Only to find you have been sold crap, inner tubes by these "big names."  I even had a Durano Plus tyre which would not seat on the rim. It slipped right off due to a weakness in the bead reinforcement until it finally went bang! Then there were the Continental 4000S tyres which went into large holes on the very first ride and punctured repeatedly. Of course Continental denied all liability. In the end the online dealer stumped up for three new tyres out of his own pocket. I kept them stored in their packaging for a year and then, when I finally fitted them, they punctured repeatedly. Thanks, for nothing, Continental and Schwalbe! Keep taking the [easy] money from your customers. You know, the one's who pay your [inflated] salaries!

Click on any image for an enlargement. 


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