I tow a coachman 575 VIP caravan 1600kg + and I just leave mine set to normal load, saying that the car only has two adults up front two medium sized dogs on the back seat and the full of clothes/food etc. can't say I've ever had any problems the DS is pretty robust

 

Have you actually had any warnings when running pressures which are not close to target settings ( high or low ones)? One of my tyres was several psi low on delivery but it didn't trigger any alert. I suspect the permissible range is a bit wider than it would be for an ordinary car given that off-roaders might want to drop tyre pressures to suit conditions. Perhaps warnings are only triggered if the is a sudden drop in pressure on one corner only.

 

Have you actually had any warnings when running pressures which are not close to target settings ( high or low ones)? One of my tyres was several psi low on delivery but it didn't trigger any alert. I suspect the permissible range is a bit wider than it would be for an ordinary car given that off-roaders might want to drop tyre pressures to suit conditions. Perhaps warnings are only triggered if the is a sudden drop in pressure on one corner only.

Yes when setting the high pressures I set the load setting first and you get a warning diagram with the low pressure corners highlighted. As I remember the highlighting disappeared at about 3psi from the correct pressure. No warning of high pressure when resetting to low load however.

 

Right or wrong, but my thoughts from another thread.

"The only place to get my figures from is the V5C and the GVW for the seven seater is as stated at 2640kg, the Mass in Service for my seven seater states 1954kg and that figure includes the driver, so that leaves just under 700kg payload.
So going by the above figures minus the driver it comes out at 410kg with approx 275kg to play with, so no I would not inflate to heavy load but choose a halfway figure.

LR recommend my towing a caravan to inflate to heavy load but there is only two of us, an 80kg towball (OK its rear of the axle but still way within limit) weight, plus 60kg on the back seat, that is no more than 4 people in the car so I inflate a 'little' (36psi all round on 18" tyres) to a midpoint between light and heavy. Even with 36psi all round it does not complain in the light load setting when towing.

No definitive answer really and in my circumstances the Caravan Club and LR disagree, but it doesn't take much to disagree with LR anyway :roll: "

Just returned from a 10 week European tour with the caravan, 3500 miles with an in between pressure and no warning from the TPS system that was set at low. No hiccups and stability spot on.

 

Pumping up the tyres again as we're three up with luggage and with bikes on the tow bar. Still find it somewhat alarming that normal load setting is 50psi on the rear (40 on the front), which is the max inflation pressure for the Conti tyres.

Accepting there's a safety margin, and that the tyres gain a few psi when in use, but is it such a great idea to have the normal setting (the 'comfort' setting is 37/32) right at the max tyre pressure?

 

I suspect that higher recommended pressures on low profile tyres are aimed at preventing rim or sidewall damage if you hit a rock or a kerb. It is standard practice to offer larger wheels only with lower profile tyres in order to keep the rolling radius about the same and therefore match gearing and related emissions figures without mechanical changes or re-homologation.
For some strange reason bigger wheels with low profile tyres are seen as an "up-market" feature that manufacturers insist on putting on top-spec models. Having had a sidewall destroyed by hitting a protruding concrete lump at 70 mph on a low profile set-up (45%) I know how vulnerable they can be and I was very lucky that the wheel was not damaged too.
Because the tyre is also wider the static deflection under extra load shouldn't be any greater but even if the extra deflection is the same there is far less margin when hitting something solid.

 

Is it correct that the advised pressures (the ones in brackets) changes. I've 20" wheels. Was telling me advised 37 front, and 35 rear. Mines were all a little low, so set them accordingly. Pulling out of the forecourt, I see advised were now 38 front,37 rear.

This morning when I check, there are back to 37 fron 35 rear. Do the advised settings change with temp ??

 

Is it correct that the advised pressures (the ones in brackets) changes. I've 20" wheels. Was telling me advised 37 front, and 35 rear. Mines were all a little low, so set them accordingly. Pulling out of the forecourt, I see advised were now 38 front,37 rear.

This morning when I check, there are back to 37 fron 35 rear. Do the advised settings change with temp ??

No, the dynamically changing pressures are the actual pressures, as the tyres heat up with use (pressure rises) and cool down when stationary (pressure drops).

 

I know the actual pressures change, my query is my advised pressures change slightly too ! I'll post pictures later

 

I know the actual pressures change, my query is my advised pressures change slightly too ! I'll post pictures later

No, they don't. Only one set of figures change dynamically. The 'fixed' pressures only change if you change the load setting.

 

On my car they appear to change relative to the temp of the tyre.

First image is me getting into the car. Second image is after a 30mile drive

"Advised" front and rear have increased by 3psi after the run.

 

Must be a new trick with MY20 then.

 

Mine do the same.

It's perfectly normal and the pressures will return to normal once the tyre cools down.

 

Mine do the same.

It's perfectly normal and the pressures will return to normal once the tyre cools down.

Check the photos - his 'target', fixed pressure are changing too, presumably so people don't let air out of the tyres when hot to match the cold target pressures.

 

Yes as per the manual

 

Yes as per the manual

indeed

the recommended inflation pressures change based on ambient conditions and as air temperature within the tyres fluctuates with use

Looked but couldn't find that previously, then again every time I run the iguide app, I get an update to the manual.

 

Yes as per the manual

It's a neat solution, I wonder what logic / algorithm they use to predict what the hot pressure will be.

 

I wonder do they have 'cold' values as the baseline then simply raise them by the same amount as tyres actual rise from cold to warm

 

I wonder do they have 'cold' values as the baseline then simply raise them by the same amount as tyres actual rise from cold to warm

Seems to fit from the shots above, doesn't it - often simple is easiest!