Can anyone advise on the best tyre pressures for towing a caravan (1700 Kg laden)? The tyres fitted on my Disco 5 HSE are 285/40/R22.

I see the tyre pressures for normal vehicle loading are 34 at the front and about 36/37 rear, my gut instinct is to go 35 psi in the front and 38 to the rear?

 

Are you sure? That sounds very low

My 2018 Discovery says 44 front and 50 rear...

 

I did find one site which states the pressures you refer to but all of the rest (including the vehicle’s own TPMS) say around the 33 or 34 psi mark for normal driving use.

 

On the vehicle plate it does state 44 & 50 for fully laden (7 people plus luggage). It seems a lot considering the stock Pirelli Scorpion tyres fitted state 50 psi maximum pressure?

We towed our caravan for the first time today since we bought the Disco 5, I upped the front tyres to 36 psi and rears to 38 psi and everything seemed fine. Not everything was fully loaded though as it was only a trial run.

 

I know this doesn't precisely answer your question regarding tire pressure for towing. I will share my opinion, which is that the normal pressure recommendation is for a loaded vehicle, towing or not. I tried the normal pressure recommendation in an unloaded vehicle and I found the ride to be harsh. I've included pictures of the TPMS suggestions and the pressure I use unloaded. I have the TPMS set to "light." I have pulled a light trailer for a short distance like this and it felt perfectly fine. Again, the vehicle itself was unloaded. I run 255/55R20 Michelin Defender M+S. It looks like my right rear could use a pound!

 

Yes. Per above there are two settings. Light and normal. We drive on normal all the time. Typically just our family (5 people) without much other luggage. Have done it for 5 years with no issues. Ride is firm but air suspension seems to manage that fine.
I can see doing lite for normal driving. But if I were towing I would definitely do the 'normal'.

 

I have running the normal pressure setting when towing my RV now over the past year. I usually drop it down to the light load in between towing/family hauling duties and that does help with some of the crappy roads we have in Houston. (glad i only go into that city from time to time now). No issues with towing and the D5 is a solid tow platform.