Which tyre pressures?

[Gravemaurice]

I did find an old thread for tyre pressures but it would not be resurrected so here's my question.

 

My Elddis Autoquest 140 has three different sets of tyre pressures -

 

Continental Vanco Camper tyres say 69psi on them

Peugeot Boxer cab says 72/73

Eddis book says high 70's (sorry its not to hand)

 

The van was supplied new with lower pressures than any of the above.

 

Which should I go with and my natural concern is about putting 10psi more in the tyre than the manufacturer has printed on the side?

 

Thanks.

 

 

 

 

 

[Madge Gentle]

Don't go by the figures on the label... visit a weighbridge (£5) and note the actual axle weights... then contact the TYRE manufacturer for the relevant pressures.

 

The following is the reply from a Product Support Engineer of Continental Automobil.

 

The pressures you require are as follows:

 

Front: 3.25bar - 47psi pressure applicable to a maximum permissible load of1590kg. 1850kg Max loading at 4bar - 58psi (1875kg maximum at this pressure)

 

Rear: 4.25bar - 61psi pressure applicable to a maximum permissible load of1970kg. 2000kg Max loading at 4.5bar - 65psi (2060kg maximum at this pressure)

 

As a general rule for pressures on this tyre, every 100kg added from the base figure of 1490kg at 3bar (43.5psi) will require an increase of 0.25bar(3.6psi) in pressure up to a maximum of 2060kg at 4.5bar (65psi)

 

With the weights I have I run my Continental tyres - Front 51psi (3.5 bar) Rear 61psi (4.2 bar).

 

 

[Derek Uzzell]

Gravemaurice

 

I assume your Autoquest’s tyres are Continental “VancoCamper” 215/70 R15CP 109R

 

For this tyre the data in Continental’s technical handbook indicate an inflation pressure of 4.75bar (69psi) being appropriate to a ‘single-wheel axle’ load of 2060kg (matching the tyre’s 109 Load Index) for a motorhome’s front axle. For the rear axle (also ‘single-wheel’ type) for a load of 2060kg Continental advises that a 5.5bar (80psi) inflation pressure would be appropriate.

 

You’ll also see that, on the Continental website, the VancoCamper section

 

http://tinyurl.com/kmhph4p

 

refers to “...up to 5 bar of pressure...” (73psi).

 

(In fact, I'm pretty sure that's a misprint, as one VancoCamper size (215/75R16C) can definitely be inflated to 6.0bar.)

 

There would be no safety-related implications if you chose to use the Peugeot inflation recommendations with this tyre, nor the Elddis ones (I'm guessing 72psi for the front axle and 80psi for the rear as those figures are commonplace).

 

The pressure-to-load advice provided to Madge Gentle does not relate to a VancoCamper ‘camping-car’ tyre with the specification I gave above, but to an ordinary Continental ‘white van’ tyre with a 215/70 R15C 109/107R specification (eg. a Continental “Vanco-2”)

 

As Madge suggests, if you wish to match tyre pressures to real-world axle loadings you’ll need to measure those loadings when your motorhome is in ‘holiday trim’.

 

[Brock]

Whatever pressure you use, ensure it is within the capability of tyres. I found reading tyre walls is an acquired dark art which I'm still learning so I still rely on internet searches for the explanation. So be very clear about the maximum pressures for your tyres and don't exceed them.

 

I'd go with either the Vanco or Elddis figure until I could get down to a weighbridge. However, you may find the ride harsh at the higher end on the front axle unless fully loaded given the state of UK roads [at least]. I paid £12 at an Animal Feeds factory for the overall van and the rear axle to be weighed; the front axle is the difference between the two. Most weighbridges will understand what you want.

 

Using the factory and my methodology was never going to give me an accurate figure but it is reasonable enough. In holiday trim, you need to include everything you would normally take on holiday including food, clothes, accessories, full gas tanks [if possible], full fuel tanks, fresh water tank with whatever you carry [25l is a reasonable amount for touring unless you are wild camping] and the right number of passengers.

 

Make sure you are running within your axle loadings and overall loading. It's not unknown to get an unpleasant surprise when weighing fully loaded. Being pulled over by VOSA and being overweight is even more unpleasant.

 

Once you get your axle weights, get in touch with the tyre manufacturer and it will give you the figures for each axle. They are used to such telephone calls.

 

I should run on 61psi front & 80psi rear if I follow my van manufacturers guidance. Michelin said I could go as low as 53psi on the front by I tend to run at 58psi. Michelin also insist on 80psi rear because there is a higher risk of overloading.