O/t Trailer tyres

[chade]

Hello,

How much do cracks matter in the wall of a tubed tyre? Would it still be OK as a spare?

TIA.

[Richard]

If I were unsure of the suitability of a tyre, I'd replace it rather than risk it.

[newshound]

Depends on the number, extent, and depth. Not good if you can see the reinforcing fabric. I'd be more relaxed about using it as a spare because you can decide to slow down if you need to use it, and minimise the distance driven.

I've just checked and I have some *small* cracks visible in the side-walls of the original rear tyres of my 3 year old car, and they have enough tread for another couple of years. They didn't bother the recent MOT tester, and they don't worry me.

Can you get a second opinion from a responsible petrol-head, or a garage that you trust?

You still havn't given us details of the trailer. The "bar" would be higher and the attitude of the police a bit more serious if you were towing, say, a two ton car behind a Transit compared to a small two wheeled unbraked camping trailer containing a small tent and not much else.

[newshound]

What about if you were only very slightly unsure?

Some cases are more black and white. If you don't know whether some mains wiring is live, you should certainly either isolate it or test it before touching it.

But this is much more grey. If you have just spent a million pounds on a yacht, then replacing a trailer tyre should be a no brainer.

This is basically the same as deciding whether to replace a car tyre. Obviously, if you cause a fatal accident and are demonstrably negligent, you deserve all the consequences.

My concern in this case is that we can't really judge whether the type and the condition of the tyre makes it suitable for the load and speed, or even whether the OP knows what the tyre pressures should be.

But a counsel of perfection, like "if in doubt replace it", means that someone who is very cautious might end up being very wasteful.

Heaven forbid that anyone following NG advice should have a serious accident as a consequence, but I think it is better if people are encouraged to ask questions, and not be put off by critical responses.

[tabbypurr]

is it this one?

NT

[Tim+]

As long as there's no cord showing sidewall cracks are permissible for car MOT and *probably* aren't significant. I would have thought it would do fine as a trailer spare.

Tim

[The Natural Philosopher]

MOT failure usually

[Richard]

OK. Perhaps I should have said that he take it to an expert to be assessed.

[Tim+]

A) No MOT for trailers.

B) Even in cars, only if ply or cord is exposed.

Tim

[alan_m]

Having watched (again) 'The World's Fastest Indian' yesterday small cracks in the side wall can be covered with Kiwi black boot polish and the tyre will suitable for your next 200mph record attempt :)

[newshound]

The most accessible "expert" is likely to be a tyre dealer and you know what they will say.

And I suspect most MOT testers will err on the side of caution, unless they know you.

Tim has confirmed that the MOT fail criterion is "visible cord" (which is what I suspected).

[Adrian]

Photo.

If the tyre's not good enough to use, it's not good enough for a spare - because a spare that's not actually good enough to use is just wasted weight and space.

If they're just tiny surface cracks, go for it - a set of Coopers I bought new last year are starting to show surface cracking near the bead. But if they're deep, bin 'em.

What's a hundred quids worth of new tyre compared to a blow-out, damaging the wing of the car if you're lucky enough to avoid the barrier or oncoming traffic?

[Adrian]

Sorry, forgot it was a trailer. Even worse. If a trailer tyre (single axle?) lets go suddenly, even at 50mph, then your underwear is definitely never going to be the same again.

[Scott M]

Depends on the trailer. My box trailer has its wheels so far back from the hitch and is sufficiently wide compared to its height that I suspect I might not notice a blow out at speed! Similarly a box trailer that does 20 miles a year and only ever does 30mph to the tip is worth leaving until the cracks become deep.

Single axle caravans and boat trailers (very high CoG) I'd be more paranoid about though (although I loathe towing both with a passion!)

And, having said all that, unless one carries a trolley jack & spare (and probably pump too!), a lost trailer tyre is a massive PITA compared to a car blowout so any trailer that does any distance ought to be kept on top of.

[robgraham]

Having had two blow outs on separate trailers in two years, one on a motorway which ended up with material on the road - embarrassing and worrying - I wouldn't take any risks now.

I seem to remember somewhere seeing a comment that a tyre was basically good for 4 years and after that you aren't quite so sure.

Rob

[Tim+]

Common cause of blowout is overloading and/or underinflation. Age of tyre may be a factor as well of course.

[The Natural Philosopher]

Is that so? Its not rue in other parts of the world..

It generally is.

[Tim+]

But this is a UK group so what's your point?

Not at all. There are many campervans and other low use vehicles going around with sidewall cracks that don't expose the ply. Mostly due to prolonged UV damage which just affects the surface.

Got any more mis-information to share? How about your interesting theories of diesel engine induction systems? I enjoyed that bit of nonsense.

Tim

[Adrian]

Must have a hell of a lot of noseweight, then - damn near unusable with anything remotely normal, with a ~50kg nose limit.

[philipuk]

If it's a trailer tyre it's probably got a low speed rating and might be quite small so might be quite cheap. Have a look on blackcircles and see if it's cheap enough to just replace for your peace of mind.

Philip