I keep hearing it said by folks on forums such as UKCS that 6 or 8 ply tyres should be fitted to caravans. On the other hand, many caravan manufacturers fit car tyres from new (where they are available in an appropriate rating).
My understanding is that reinforced or 6/8 ply tyres need to be pumped up to higher pressures, as the side walls are stiffer and hence generate more heat for a given inflation pressure, load and road speed. Running tyres at a higher inflation pressure will reduce the tyre footprint, affect the suspension dynamics and transmit more road shock into the caravan itself. I'm not convinced that this is a good thing.
Where caravan manufacturers fit appropriately rated car tyres to a new caravan after taking advice from the tyre manufacturer, why do so many caravanners seem to think that they know better when worrying about tyre replacement?
Despite having a lengthy ponder about this, I cannot come to a conclusion that stacks up. Any thoughts?
Andrew
(Confused of Oldham)
excert from caravan club information(which i think is a reputable sorce)
http://www.caravanclub.co.uk/nr/rdonlyres/aa21c69d-adcd-4264-9be5-090bdec6ef81/0/tyresandwheels.pdf
What do caravan tyres do? Surprisingly, perhaps, caravan tyres do their job is a different way to car tyres, and need to be treated differently, as a result. On a car, the tyre‟s traction (if it is on a driven wheel) is important, but caravan wheels are not powered. All the wheels on a car, but especially the front ones while steering need tyres which grip well particularly on wet or slippery surfaces – this is much less important on a caravan (although not entirely irrelevant, of course). Car tyres need to cope with higher cornering forces than are ever likely to be seen by a caravan, too. Also, if your car tyres generate lots of road noise, you will be aware of it, whereas on your caravan you would not. Cars tend to have much softer, more compliant suspension than caravans, and have sophisticated shock absorbing. Most caravans have simple, relatively basic suspension, with relatively little inherent shock absorbing characteristics (whether or not the caravan is fitted with separate shock
It is best if your caravan tyre does not end up like this….
3
absorbers). In practice, therefore, caravan tyres tend to provide a significant proportion of the shock absorbing capacity of the suspension, making their characteristics and crucially their inflation pressure particularly important. In essence, the harder you pump up your caravan tyres, the stiffer you are making your shock absorbers. Caravans do a fairly low annual mileage – on average around 2000 miles a year, so it would take many years of use to wear out the tread. However, two or three factors make them deteriorate in a different way, even with careful use. All tyres age and deteriorate due to exposure to sunlight and atmosphere, even if not used. Caravan tyres can suffer fatigue due to the repetitive small impacts they suffer in everyday use, without the protection afforded by the more sophisticated suspension found on cars. Also, being stored for long periods of the year without use can put undue strain on one particular part of the tyre. For all these reasons, caravan tyres need to be specified with care, used with sensitivity in terms of loading, inflation pressure and speed, and properly cared for when not in use. They also need regular replacement, irrespective of their visual appearance, as detailed below.