Tyre Safety ??

[GregC]

We purchased in July this year a 2005 Fleetwood Volante 560-4, from a Fleetwood dealer. Returning from holiday in September we experienced a blowout whilst travelling at 50-55mph on the Peterborough ringroad. Fortunately we have Tyron bands fitted, so the tyre stayed on, we pulled off the road, and with the spare fitted, thanks to Green Flag, we were soon on our way home.I took the van to have new tyres fitted and was told that the other one was showing the braids and would soon have burst!.We replaced the tyres with identical Hancook RA08 165x14 8pr 97P to those fitted, which due to the van's age I assume to be the originals. Whilst looking at these tyres when we were back home I noticed that the weight rating for these tyres on a single axle is 730kg. The MTPLM of the caravan is 1460kg,so there is no safety factor built in by the manufacturer at all, and theoretically if I overload the caravan by just 1kg I will be overloading both tyres. The caravan handbook says the tyre pressure is 65psi which is the max pressure stamped on the wall of the tyre, so we are running the tyres at max pressure, and probably max loading most of the time, so it is no wonder they have only lasted 3 years.The tyre company that fitted them said it would be better to run them at 60psi, but the Caravan Club and Fleetwood say it must be 65. CC also suggested that when I replace them I sould try a larger size tyre. But surely it is the Manufacturers responsibility to fit a safe tyre to their product. All Fleetwood say is basically 2x730 = 1460 and if I dare to overload it by 1 kilo then I should be locked up!!!.

 

[rob_jax]

Hi Greg,

Well there several points to this:

The legal maximum weight for the caravan is the MTPLM you quoted and you must never exceed this weight, even by 1 kg.

The load index of the tyre applies at the speed rating - in your case P - or 93 mph - which means your tyres have an extra measure of safety at 60 mph

But even so, nest time I'd be tempted to fit a higher rated tyre - our 1200kg MTPLM Eriba is fitted with 195/70R14 tyres - with a substantial load index margin - and a normal inflation pressure of 3 bar - about 45 psig

Robert

 

[Lutz]

Firstly, chances are that when you had a blowout, the tyre would have remained on the rim even without Tyron bands. (The apparent benefit or otherwise of Tyron bands was the subject of a recent thread so I won't go over all that again).

Secondly, there is no need for a safety factor on the weight rating because even if the tyres had a higher rating, you would still be breaking the law if you exceed the MTPLM. So what's the point of having a safety factor if you are already illegal anyway, although I doubt whether you get locked up if you exceed the limit. Besides, the maximum load applies at the maximum permissible speed that the tyres are also rated at. You don't mention the speed rating, but it is very likely to be more than the 60mph at which you are allowed to tow the caravan. Therefore, you would already have a safety margin by taking into account the lower speed.

As for the tyre pressure spec, the tyre manufacturer's recommendation is a compromise between ride, roadholding and wear characteristics encountered in normal use on a car or van. However, wear is not normally an issue with caravans because their tyres are usually replaced well before they are worn. A slight increase in pressure, in line with the CC and Fleetwood's recommendations benefits stability.

 

[Lutz]

Firstly, chances are that when you had a blowout, the tyre would have remained on the rim even without Tyron bands. (The apparent benefit or otherwise of Tyron bands was the subject of a recent thread so I won't go over all that again).

Secondly, there is no need for a safety factor on the weight rating because even if the tyres had a higher rating, you would still be breaking the law if you exceed the MTPLM. So what's the point of having a safety factor if you are already illegal anyway, although I doubt whether you get locked up if you exceed the limit. Besides, the maximum load applies at the maximum permissible speed that the tyres are also rated at. You don't mention the speed rating, but it is very likely to be more than the 60mph at which you are allowed to tow the caravan. Therefore, you would already have a safety margin by taking into account the lower speed.

As for the tyre pressure spec, the tyre manufacturer's recommendation is a compromise between ride, roadholding and wear characteristics encountered in normal use on a car or van. However, wear is not normally an issue with caravans because their tyres are usually replaced well before they are worn. A slight increase in pressure, in line with the CC and Fleetwood's recommendations benefits stability.

As Robert correctly pointed out, the speed rating was mentioned. It was something I overlooked.

 

[Chrisbee]

Greg, the weight rating is for individual tyres, not the same as max weight divided by 2. Unless you are sure that the weight is equal side to side in your van you could be in trouble. Allthough as others have said there are built in margins, the authorities will take the load rating of the tyres as the absolute top figure,

 

[Gafferbill]

Point well made Chrissbee.......

Caravans often have unequal weights bearing on each tyre dependant on internal layout and loading by the owner.

Greg does not have a sufficient margin of safety

 

[GregC]

Point well made Chrissbee.......

Caravans often have unequal weights bearing on each tyre dependant on internal layout and loading by the owner.

Greg does not have a sufficient margin of safety

Perhaps you would like to explain that to Fleetwood, they are quite confident that all is OK

 

[Gafferbill]

Greg

It is about a safety margin and what you are happy with.

Fleetwood say you are OK largely because you are towing well below the speed rating for the tyre fitted.

I simply agree with Robert and would want higher spec tyres for an even greater margin to minimise tyre trouble.

 

[ProfJohnL]

A small point is that the caravans MTPLM is the static total weight of the caravan.

Part of that load is used to produce the nose load so in fact the wheels are only carrying the MTPLM minus the nose load.

I know its only a relatively small amount but it works in your favour.