OT: tires

[The Natural Philosopher]

Might be a jag

[mm0fmf]

I can code my car to use ABS pressure monitoring and disable the TPMS sensors. All the software is built in for either, just a matter of enabling it. Depends how much sensors are when I need them whether I code it or get new ones fitted.

[Dave Liquorice]

I haven't got asymetric tyres or a BMW...

[Brian Reay]

Our Smart Car has different tyres front and rear. A bit of a nuisance really. I carry a 'space saver' spare which is safe for both- I don't trust the gunk stuff which is supplied these days in lieu of a spare.

[mm0fmf]

Never knew they did it too. BMWs are famous for it.

[mm0fmf]

Different Daves... that's causing some confusion. Mind if I call you Bruce? ;-)

[Max Demian]

A tractor? ;->

[The Natural Philosopher]

Think my XKR had different front to rear and different left to right as well

[The Natural Philosopher]

Drag race funny car?

[Dave Liquorice]

True enough but not on my car with its wheel/tyre size. The door label and manual both say 35 psi all round for all loads and speeds. But 35 psi on the front is 2 psi too low according to the tread wear.

[Andy Burns]

And that if you ever run them on flat, you need to replace them ...

[Andy Burns]

I bought one of those once ... never again.

[Michael Chare]

My relatively new VW has rubber valves but there must be sensors inside the wheel. If I put on my winter wheels which don't have sensors I get a warning light on the dashboard, just as described in then manual. The warning system can not be deactivated.

[Andy Burns]

yesbut, I'd trust the car manufacturer to know sufficient about the type of tyre they've chosen for the vehicle to make a good recommendation for the pressure.

[The Natural Philosopher]

I'd trust the tyre manufacturer to know what pressures his tyres would run best at on that car...

Who is more likely to have tested that tyre on that car?

Tyre pressures are not exact anyway.

Did you see that TV documentary in a couple who got stuck in sand in an Australian desert and died?

The team that found them dropped the tyre pressures to 5 psi and just drove the car out...

[T i m]

<snip>

You say that because you probably don't really understand how a tyre is made and what weakens the structure or not?

Remove your need to obey the rules (that may well be out of date, out of touch or overly biased because of people not being able to make educated decisions etc) and things could be very different.

Example, did you know the current British Standard for motorcycle safety helmets force riders to wear helmets that are *more dangerous* than others that are already out there but aren't approved for road use?

So, by disposing of a tyre that could otherwise be repaired is seen as being safer (better to be safe than sorry) but how do you test / prove that a tyre repaired to the current standard is any safer than one that isn't (assuming the alternative is shown to be a perfectly valid repair and *could* even prevent the tyre being weakened in the first place before being repaired traditionally)?

<snip>

Quite. Doesn't stop people ignoring the warning though eh!

No, can you?

wiskey-dave, is that you? ;-)

We can't consider the invisible and you might try to take your 'must abide to the rules' head off for a while and consider what's actually going on at a practical level.

Perfectly sound tyre, correctly inflated, picks up a fine nail in the middle of the tread area (that passes between the belt cords) but causes a loss of air. Un treated tyre starts to deflate and ignoring TPMS fitted vehicles for a moment (as some people do it seems, according to this thread) the tyre is run at high speed for some time, causing the tyre to overheat. Assuming the issue is spotted before the tyre fails, you try to find a safe place to stop and try to change the spare (if you have one) or wait for the recovery service to attend and get you going again.

But what if the tyre was able to instantly seal itself? What risk would you be at then? All you had was a hole though the rubber that let the air out and now you aren't letting the air out? This is *NO* different to the millions of inner tubes that are used worldwide on tyres with all sorts of holes and damage and with few issues (if used intelligently) and you can *never* fully cater for the stupid.

What would a traditional repair do that would improve anything?

The answer of course is 'nothing' to the truth is actually understanding that such things exist (and have so for years), do work and are safe.

So, lets consider some other cases, like some damage to the sidewall. Centripetal force ensures the sealant is nowhere near the sidewall and so would have no bearing on that sort of damage.

What about a big hole, like going over a piece of steel etc that is likely to do actual damage to the structure of the tyre? The solution isn't able to fix holes past a certain size but it might slow the deflation time enough to give you chance to get from the outside lane to the hard shoulder safely. In that instance, what harm could it do?

Then we have a hole (screw / nail) near enough to the shoulder that would traditionally write even a brand new tyre off. Firstly, if it actually penetrates into the inside of the tyre to form an air leak, the solution would rush out past the object, lubricating it and helping it be ejected (centripetal force again) before it does any real damage. The leak is blocked and you carry on un-effected.

Because the sealing plug has woven itself into the inside of the holes, the chances are the sealing plug cannot be ejected and IF it was, it would simply re-seal again. No deflation, no prolonged presence to the object so less damage to the structure of the tyre. Without the sealant, let's say you weren't going fast, were able to stop safely, were able to fit the spare and get the punctured tyre to the tyre place, just how scientifically do you think they would check the inside of the tyre construction (not the inside of the tyre itself) for damage pre repairing? I can't remember seeing an X-Ray machine at my local tyre place and in fact the first thing they do is run a *big drill* though the hole (often a bigger drill bit than the hole itself), ready to take the core of the repair plug?

So if you consider that 'approved repair' (and the potential overheating preamble) process to be safer than the tyre self sealing, then that's up to you.

Personally, I would rather my wife or daughter's vehicles didn't get the puncture in the first place (and both have clipped the kerb (for the same reason) and both sealant filled tyres have deflated quickly (as you would expect)).

The last thing I'd want to do is convince anyone to treat their tyres and especially if they didn't fully understand the whole process, just that all those who have done so agreed it was a very good thing.

FWIW, there are quite a few agencies who are now pre-installing such sealant in their fleet vehicles, including some of the Motobility type people. For them the risk of getting a sealable puncture far outweighs the risk of a repair failing because the tyre itself does or being caught out at the wrong place at the wrong time.

YMMV of course. ;-)

Cheers, T i m

[T i m]

I think that may depend on the 'gunk' Dave and they are by far, not created equal.

Not the case with Punctureseal and what I used to use before that, Ultraseal as they are fully water soluble and have washed out of a tyre (with a cold hose) they have been in for 8+ years. They contain no silicone or anything that would prevent in any way, a 'traditional / approved' repair being made. Why you would want to ... [1] ;-)

Again, that range can be extended, if you don't use a repair that isn't good in such locations.

It's like using a panel pin for a fixing that is in tension rather than using a screw.

The sort you maybe referring to probably are, what I'm talking about can (and has in every instance so far), provided a safe and permanent repair for the remaining life of the tyre.

Cheers, T i m

[1] I managed the web presence for one of our BMW motorcycle club members as she rode her bike (solo) round the world. Upon her return the rear tyre (and not the same she set out on as the first was worn out) was very <cough> worn and was showing the signs of at least 5 punctures. 5 punctures she didn't even know she had suffered and she road the rest of way home on because of the sealant. ;-)

[Brian Reay]

Tyre companies will, at least for heavier vehicles and things like caravans, advise you specific pressures for their tyres if you tell them the actual axle load (obtained by using a weighbridge).

Even if you only know the max axle load (from the vehicle spec/ Vin plate) and tyre details (from the side wall and reference to tables), working out what pressure you should use isn?t difficult. Those who have caravans and motorhomes, trailers etc often need to do it.

For example, my trailer isn?t fully loaded with the Smart Car on it so I need to adjust the tyre pressures to allow for the reduced axle loading.

[dennis]

Tyre pressures vary with rim width and tyre width so you need that info too.

Put two on it.

[Brian Reay]

That is accommodated for in the load rating. The tables convert it to a number (load) you use in the calculation at a the reference pressure. That then allows you to scale from there.

We sometimes load it up with wine when returning from France ;-)