Tyre pressure

About the important piece of kit under your Cape Cutter 19 when on the road.....

Tyre pressure

Postby erbster » Mon Jul 22, 2019 10:20 pm

Hi folks,

Was checking tyre pressures on my trailer today. Mine was 49psi. Looked a little soft (provides shock absorption to boat) - the manual says 65psi. It made me wonder what others use. I usually check the tyre and hub temp on a long journey and it’s never more than a bit warm and tyre wear is not uneven (though the trailer mileage is not particularly high); I’ve always towed trailers with soft tyres (see above).


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Re: Tyre pressure

Postby bellalistair » Tue Jul 23, 2019 8:16 pm

Having thought to check tyre pressures on the way home from Essex we had a little incident. Whilst topping up aiming for 55 the valve blew out of one of the tyres. Fortunately we were on the in-laws drive so an easy swap for the spare. Made me even more wary of 65 though so I'm interested in thoughts in this thread!

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Re: Tyre pressure

Postby Greybeard » Tue Jul 23, 2019 9:58 pm

If a valve blew out at that pressure it was defective. How old was it?. Valves will easily cope with 100psi or more - tyres might not though for long. If pressures are too low then flexing of the sidewalls generates heat which can lead to failure of the tyre. Too low a pressure also causes the centre of the tyre to cup putting extra load on the tread edges which wear quicker. Low tyre pressures also use extra fuel.
The recommended pressure is the one to use. A CC19 trailer is right on the weight limit of 1600kg, perhaps slighly over with a fully kitted boat. Running low pressures aint worth the risk - either of a blowout or points on your licence ;)

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Re: Tyre pressure

Postby erbster » Tue Jul 23, 2019 10:19 pm

Thanks for those comments, you are right of course. However I am conscious of the vibration transmitted to the boat and all it’s contents for potentially hours of towing. I’m confident that the tyre does not get overly warm during towing (I check regularly).

My boat is ten years old now and so are the tyres. I wonder if it’s time to replace them; they’re not worn but the rubber will be degrading.

Every time I think about a blowout, I drive a little slower...


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Re: Tyre pressure

Postby Dennis » Tue Jul 30, 2019 2:59 pm

I am 100% with Steve on this one.

Under-inflated tyres will lead to overheating (of the tyre) and increases the chances of failure. I have never heard of a valve blowing out of the rim before, it must have been either faulty or incorrectly fitted. My 1550 Kg caravan also has 65 psi tyre pressure, with exactly the same size tyre as my CC19 HM 1800 Kg trailer. I check the pressure regularly.

I have only once suffered a tyre failure on a trailer. I was towing my caravan to Hockenheim for the 2003 German F1 Grand Prix when suddenly a severe vibration was felt in the car. I realised that it was at road wheel frequency so was most likely a tyre, at that point I thought it was one of the car tyres. As it happened we were nearly at our destination and the next exit off the autobahn was for Hockenheim. We slowed down and limped to the exit and our destination. It turned out that one of the caravan tyres had failed. It was still fully inflated, but the carcase had failed causing the tyre to bulge. The caravan was only three years old and the tyre less than four years old.

It is generally recommended that tyres are changed at seven years old, although I have not yet replaced mine which are now eleven years old. :eek:

I think I might replace my tyres on the boat trailer, better safe than sorry.
Cheers

Dennis

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