Today our Troll had a new set of 3 tyres. Ordered from our local friendly tyre specialist last Friday and ready to fit this morning. Two trips to town however, first with the spare and then again with the remaining two after fitting the spare to the van and leaving one side jacked up. After much deliberation we decided to stick with the size that came with the van when new, 185/70 R13 86T.

However, I've discovered something which I find very interesting but is also a warning to others :-

As we all know, the 86T is a particular load and speed rating. 86 = 530kg (which is half the max. load of our Eriba + 6%).

The latest information from Hymer regarding tyre pressures for our particular model is 3bar cold (44psi).

The original Dunlop SP's that were supplied with the model when new have a max. cold tyre pressure of 44psi.
Therefore, I've been running the van on 44psi. as recommended.

Shock, horror, today I discovered that the replacement tyres (Runways) newly fitted to the van just before we purchased it from a dealers, although 86T, only have max. tyre pressures marked on the inside and are rated at 36psi max.

I thought load ratings and tyre pressures would go hand in glove but obviously not.
To confirm this, the tyres I purchased today, again 86T's have a max. cold tyre pressure of 51 psi. This was more by luck than judgement.
The problem is that most tyre suppliers don't talk max. tyre pressures when offering tyres for sale so beware.

Randa

That's interesting Dave. Good link.
If I've got it right then I should be putting 48 psi into the tyres.
Load rating 86 = 530kg
Tyre max. inflation = 51 psi
Weight of Eriba 1000kg

Therefore max. pressure for tyre divided by load rating....... 51 dived by 530 = 0.0962.(inflation factor)
Inflation Factor times half the weight of the caravan............0.0962 x 500kg = 48psi.

My head hurts Randa

Your maths and your reading of the load charts looks sound to me Chris.
When they came up with 1251kg they probably had a "Michelin Moment".
The 10% bit seems to be the order of today yet way back in 1999 when our van was born they decided that 6% was OK.
We overcome the 4% difference by driving hell for leather on straight roads and cornering very, very slowly
Many web sites state that because caravans have an unsophisticated suspension, they rely on the tyre side wall so going over 10% gives a stiffer ride.
What I can't get over is the variation in max. tyre pressures for the same size and same rated tyres.
Randa