Tyre pressures

[Don636]

I checked what my tyre pressures should be with both a Continental chart and the Tyresafe calculator and am somewhat concerned and confused by the difference.

 

The tyres are Continental Vanco 2 - 215/75 R 16 C 116/114R.

The axle weights are: Front - 1800 kg. Rear - 1680 kg.

 

Continental tyre pressures are: Front - 51 psi (1805 kg). Rear - 47 psi (1705kg)

 

Tyresafe pressures are: Front - 57 psi. Rear - 59 psi.

 

The difference is quite significant, especially for the rear which is higher for the rear instead of lower with Continental and it makes me unsure what to do.

 

Why is this so difficult? Any thoughts?

 

 

[Keithl]

I don't know why but the 'new' TyreSafe on-line calculator gives different figures to the old TyreSafe MH brochure.

 

Your tyre size gave 51 psi front and ~47 psi rear at your axle loads so a good match to the Conti figures.

 

Here's a link to the 'old' brochure...

 

http://www.tyresafe.org/wp-content/uploads/2015/12/motorhome-leaflet.pdf

 

Keith.

[Don636]

Thanks Keith that looks better, wonder what's up with the new Tyresafe calculator.

[Keithl]

Don636 - 2018-05-31 9:05 PM

 

Thanks Keith that looks better, wonder what's up with the new Tyresafe calculator.

 

Why not email them and ask why such a big difference?

 

https://www.tyresafe.org/contact/

 

Keith.

[747]

Don636 - 2018-05-31 7:48 PM

 

I checked what my tyre pressures should be with both a Continental chart and the Tyresafe calculator and am somewhat concerned and confused by the difference.

 

The tyres are Continental Vanco 2 - 215/75 R 16 C 116/114R.

The axle weights are: Front - 1800 kg. Rear - 1680 kg.

 

Continental tyre pressures are: Front - 51 psi (1805 kg). Rear - 47 psi (1705kg)

 

Tyresafe pressures are: Front - 57 psi. Rear - 59 psi.

 

The difference is quite significant, especially for the rear which is higher for the rear instead of lower with Continental and it makes me unsure what to do.

 

Why is this so difficult? Any thoughts?

 

 

From practical experience I would go with the higher pressures, the lower ones seem too low. If you were to lower the pressure to the lower figures, I reckon your tyres would look obviously underinflated (bulging sidewalls).

[colin]

747 - 2018-06-01 8:58 AM

 

Don636 - 2018-05-31 7:48 PM

 

I checked what my tyre pressures should be with both a Continental chart and the Tyresafe calculator and am somewhat concerned and confused by the difference.

 

The tyres are Continental Vanco 2 - 215/75 R 16 C 116/114R.

The axle weights are: Front - 1800 kg. Rear - 1680 kg.

 

Continental tyre pressures are: Front - 51 psi (1805 kg). Rear - 47 psi (1705kg)

 

Tyresafe pressures are: Front - 57 psi. Rear - 59 psi.

 

The difference is quite significant, especially for the rear which is higher for the rear instead of lower with Continental and it makes me unsure what to do.

 

Why is this so difficult? Any thoughts?

 

 

From practical experience I would go with the higher pressures, the lower ones seem too low. If you were to lower the pressure to the lower figures, I reckon your tyres would look obviously underinflated (bulging sidewalls).

 

Having run the same tyres on the same base van I would agree.

[Steve1893]

All this really confuses me too as there's just so many contradictory figures to my simple mind anyway!!

 

I picked up my new Elddis 185 Platinum Edition a few weeks ago and I've found the ride far too harsh/firm. The tyres are Continental Vanco Campers 215/70/R15 CP's 109 load index. The passenger door plate dictates pressures of 75 psi front and 79 psi rear. I've checked all four tyres and they're all at 80 psi as collected from the dealership.

 

Before a short trip last week, I visited my local weighbridge fully loaded (Mrs B and I, full fuel and fresh water tanks and all kit/provisions we needed for 3 nights away). We weighed in at 3360kg, 1540 front axle and 1820 rear axle, van max is 3500 overall, 1850 front, 2000 rear.

 

 

 

Here's what causes my confusion......Tyresafe website for my axle loads calculates 54 psi front and 80 psi rear - the advice under the result they show says the following...."CP-type tyre construction enables the use of higher inflation pressures to provide resistance to the difficult conditions of use encountered on motorhomes. Therefore, when CP-type tyres are fitted on the rear axle in a single formation set the inflation pressures to 5.5 bar (80 psi) for all loads".

 

However when I emailed Continental, they replied with the following..."I am afraid you have been given incorrect information, the inflation pressure, regardless of axle, will always be related to the load placed on the tyre.

With a 'CP' type tyre the rear axle inflation pressure is higher than the fronts for the same weight but it is still related to the weight placed on it.

 

Based on your figures the recommended inflation pressure is:

 

Front: (1540Kg) > 3.5 bar (51 psi)

Rear: (1820Kg) > 4.75 bar (69 psi) "

 

 

So I have Peugeot telling me 75 front 79 rear on the door plate, the dealership (presumably) setting them at 80 front and rear, Tyresafe saying 54 front, 80 rear and Continental advising 51 front and 69 rear - all a bit confusing!

 

 

I've decided to trust Continental and reduce to 51 front and 69 rear, based on the fact that my axle loads when I weighed in were what will be pretty much max for me at any given time. Hopefully this will make the ride a bit more pleasant without compromising safety but I'm still surprised that there seems to be so many differing views.

 

 

 

 

[747]

There is a simple check to see if you are in the right area for tyre pressure. No doubt you have seen the diagrams on the tyre sites that show the shape of tyres that are over, under and correctly inflated.

 

Measure across the tread area of your tyre.

Find some smooth Tarmac.

Put a heavy strip of chalk across the tread and drive one revolution of the wheel.

Measure the width of the chalk mark.

 

It should be slightly shorter than the measurement you took of the tread width. That is because of the tyre profile. Underinflation will give the same width as your measurement. A much shorter measurement will indicate overinflation.

[Derek Uzzell]

Steve1893 - 2018-06-01 11:12 AM

 

...I've decided to trust Continental and reduce to 51 front and 69 rear, based on the fact that my axle loads when I weighed in were what will be pretty much max for me at any given time. Hopefully this will make the ride a bit more pleasant without compromising safety but I'm still surprised that there seems to be so many differing views.

 

 

If your Elddis motorhome has TPMS, you should anticipate that reducing its tyre pressures to 51psi(front) and 69psi(rear) will cause the TPMS system to issue ‘low tyre-pressure’ alerts - most probably for the front tyres as you’ll be reducing from 72.5psi right down to 51psi.

 

Suggest you refer to this concurrent forum thread

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/TPMS-/49489/#M568129

 

 

[Steve1893]

Thanks Derek, useful threads.

I'm fortunate as my model (dealer-specific edition) doesn't appear to have the TPMS . There is no mention of TPMS in my boxer manual either. I've adjusted to 51 front 69 rear and no warning lights or alarms as yet :-)

 

 

[Don636]

"From practical experience I would go with the higher pressures, the lower ones seem too low. If you were to lower the pressure to the lower figures, I reckon your tyres would look obviously underinflated (bulging sidewalls)."

 

I have lowered my tyre pressures to a couple of pounds over the Continental figures and there does not appear to be any excessive bulge at the bottom of the tyre. I understood that all tyres will have a bit of bulge at the bottom even with correct pressures due to the construction of the tyre.

[747]

Don636 - 2018-06-01 3:23 PM

 

"From practical experience I would go with the higher pressures, the lower ones seem too low. If you were to lower the pressure to the lower figures, I reckon your tyres would look obviously underinflated (bulging sidewalls)."

 

I have lowered my tyre pressures to a couple of pounds over the Continental figures and there does not appear to be any excessive bulge at the bottom of the tyre. I understood that all tyres will have a bit of bulge at the bottom even with correct pressures due to the construction of the tyre.

 

If you are happy then I'm happy too. :D

[Derek Uzzell]

Steve1893 - 2018-06-01 2:56 PM

 

Thanks Derek, useful threads.

I'm fortunate as my model (dealer-specific edition) doesn't appear to have the TPMS . There is no mention of TPMS in my boxer manual either. I've adjusted to 51 front 69 rear and no warning lights or alarms as yet :-)

 

It no longer seems to be possible to access on-line Owner Handbooks for Citroen/Peugeot vehicles but, as Peugeot Boxers have had a TPMS option for several years and the Boxer handbook will be ‘generic’ for the Boxer range, there ought to be a reference to the system in your motorhome’s handbook. The acronym “TPMS” may well not be used though - look for a reference in the index to “Under-inflation detection” (perhaps in the handbook’s “Driving” section).

 

Since mid-2014 - when ‘X290’ Boxers/Ducatos/Relays were introduced - there have been regular complaints on motorhome-related forums about the TPMS system fitted as standard to Boxer-based motorhomes made by Auto-Sleepers, Bailey and Elddis, and how that system inhibits reducing the factory-advised tyre pressures to gain a less harsh ride. For example

 

https://www.caravanclub.co.uk/club-together/discussions/information-technical-tips-advice/motorhomes/2017-peugeot-boxer-low-tyre-pressure-warning-lamp/

 

(Incidentally, some of the advice in that discussion is wrong...)

 

When you turn on your motorome’s ignition a batch of symbols will illuminate on the dashboard’s instrument-cluster as the vehicle carries out a ’system check’. Some of those symbols will stay illuminated until the driver performs an action (eg. starts the motor or releases the handbrake) while other symbols will cease to illuminate provided that the sub-system to which the symbol relates is ‘considered’ by the vehicle’s computer to be functioning normally.

 

The format of dashboard symbols has been standardised

 

http://www.carbuyer.co.uk/tips-and-advice/152578/car-dashboard-warning-lights-the-complete-guide

 

and I’ve attached a picture of the symbol that relates to a TPMS system.

 

If your Elddis has TPMS, then I’d expect the TPMS symbol to appear briefly on your motorhome’s dashboard display when the ignition is turned on.

 

Even if your Elddis had the TPMS feature, there’s no certainty that the system would be in full working order, nor (assuming it were working) for the driver to know what pressures the system had been set to. The only satisfactory way to establish either of those factors would be for a Peugeot agent to check using their technical equipment.