Tyre age and load ratings.
Now that Christmas is over, it‘s time to start thinking of the new touring season and, in our case, replacing the 5 year old tyres on our Troll.
There is a line of though that suggests that tyres need not be replaced for seven years. In the October 2014 issue of the Camping and Caravanning magazine it states that in “the caravan industry five years is seen as a sensible time for changing, especially for tyres operating at 50psi or more. The maximum age for any caravan tyre is seen as seven years - the five-year recommendation allows for a tyre to be up to two years old when it’s fitted.” (page 68)
I wonder how many of us check the date on “new” tyres, when they are fitted?
There are also some interesting points regarding tyre loading. I have been considering fitting tyres with a greater load rating as some other Eriba owners have. We currently have manufacturer specified 530kg rated tyres but to me that seems to be a little too close to the 1000kg gross weight of the van. However the above mentioned issue of the C & C magazine states that “replacement tyres should match the original specification of the vehicle manufacturer. Tyre fitters may suggest tyres with a higher load rating but bear in mind they could give the vehicle a harsher ride.” (page 68). I’ve also read elsewhere that a stiffer wall tyre could damage the suspension. I would appreciate any comments regarding this.

Still on the subject of tyre load ratings, it was interesting to read on a CC publication that the load rating of a tyre is assessed when the tyre is at its full running speed rating. So in the case of my existing tyres (86T), the 530kg max. load rating is measured when the Eriba is doing 118mph , any less speed and the load rating improves.
This raises the subject of “bonus load”. Although still legitimate in the UK (but not necessarily abroad), it is now frowned upon. Bonus load was often used as a legitimate way of using lower load rated tyres as caravans are only allowed to travel at 60 mph in the UK. However, they may be deemed illegal in other countries because of the greater maximum speed allowances.

Regarding the subject of tyre pressures, we are all aware that the more Hymer/Eriba pressure charts we study, the more confused we are but I came across this Caravan Chronicles Blog recently which suggests that there should be a max. tyre pressure rating on tyres. With this rating, the tyre pressure can be calculated. However, I can't find any reference to tyre pressure ratings on my existing tyres.
Randa

Thanks for your reply Gray. It looks like you are slightly worse off than I am. Mine give me a 6% safety margin whereas yours only give you 3%. I think the recommendation is 10% but there appear to be popular sizes and ratings and tyres that fall between these standard sizes and ratings are hard to come by.

I'd be grateful to hear what others think about going for a tyre with a far greater load rating. I'm inclined to stick with what was on the van but after the problems I experienced with one of my tyres last year, I'm unsure as to what to go for.

Regarding tyre pressure codes, I've looked around the interweb and it would appear that Max. tyre pressure symbols on tyre side walls are only obligatory in the USA ( along with a few other markings ).

Randa

Quote: Steamdrivenandy wrote in post #6

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I recall that I got a new set of tyres for my '05 540 when I purchased it in 2011. I sought the advice of Sandy @ Jandi and he advised to go for the tyres fitted to current 540's which were a slightly different size/type to those fitted to earlier vans. They still fitted the wheelarch/mover etc and had a stronger weight limit. I'm sorry I can't remember the details now.

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Zitat

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Quote Pepe le Pew:-For what it's worth, I don't subscribe to the five-years and bin them school of thought either.

These Kargomaxes were seven in December (they are dated week 51 of 2007), but show absolutely no signs of fatigue or aging as yet. There is no cracking whatsoever between the tread blocks or on the sidewalls, though if I do find any I'll almost certainly change them immediately.

I appreciate that caravan tyres are the subject of very different conditions to those which affect the tyres on a car in fairly constant use, but notwithstanding that I do think there is probably rather too much self-interest involved in the advice dished out by tyre retailers.

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To reinforce (no pun intended) this argument, when we found out that our spare wheel had an unused Dunlop SP tyre dated 1998 on it we had it examined and passed by our local friendly Tyre Specialists. When we had an unexpected problem with one of the 5 year old road tyres whilst in Barcelona, our only immediate option was to run on the spare. That spare brought us well over 1000 miles back home without any problems and since having it re-inspected has served us with an additional > 800 miles since our return. We have been advised to keep it as a spare when we renew the road tyres.
Randa

Zitat

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Quote Logburner:- My only concern is the Max. pressure of 40 psi.written on the sidewall.

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That's interesting Ian. I can say that I've not discovered a max. pressure symbol on our tyres. I aim to carry 3 bar (44psi) in our tyres as it seems to be around the most popular figure used. However, we've got an older 1000kg van with 13" wheels.
I hadn't thought of it before but it's interesting what Pepe le Pew said earlier, i.e. he carries less pressure in his tyres because his tyre load values are far greater than they need to be. Therefore I suppose if your tyres are rated 18% above the gross weight of the van then perhaps 40psi is OK.
Randa

Quote: Randa france wrote in post #13

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I hadn't thought of it before but it's interesting what Pepe le Pew said earlier, i.e. he carries less pressure in his tyres because his tyre load values are far greater than they need to be. Therefore I suppose if your tyres are rated 18% above the gross weight of the van then perhaps 40psi is OK.

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