Advice Needed From BMW Sidecar Enthusiasts

My rig is nothing like yours, but they all have some common traits.  You want the bike suspension to match the sidecar suspension. The sidecars normally don't have as much suspension travel as the bikes and the suspension on the car is usually fairly stiff.  So you will want to set up the sag on the bike, so that you only have about 1" sag on the front and rear. The bike suspension needs to be stiffer with a sidecar. It is not uncommon on a sidecar rig ( without the modern electronic adjustments ) to have to go to a heavier rear spring on the bike.  With the BMW electronic suspension adjustments you likely don't have to go that route.  So in your case whatever mode stiffens the suspension would likely work.  You don't mention if you have adjustable lean as that can help in some situations like high winds, heavy loads etc. You likely had to play around with your previous rig to get it to handle the way you wanted, your new rig is no different.

As to tire pressure.  Car tires are likely to run in the area of 32 lbs or so, front bike tire 33-35 or so, rear motorcycle tire 36 or so and the sidecar tire will depend on its size.  For example on my Kenna single car, it has a 12 " tire and I run about 25 lbs empty or loaded.  That particular tire if you where using it on a trailer would be around 50-60 lbs. The sidecar is so light it doesn't need anywhere near that much air pressure. Basically you need to run enough air to keep the tire on the rim under side loads. With the rig you likely will want to play a bit with the air pressure as a couple of pounds either way can make quite a difference.

My rig, 1995 BMW R100RT with a Kenna single, leading link front end, is set up on the stiff side and I likely don't have 2 " of travel on the rear suspension of the bike.

A friend of mine had a 09 GS 1200 with a DMC sidecar and the electronic lean on the rig, along with the electronic suspension on the bike.  He found that he had to use the electronic lean a lot.  Whereas a manual rig like mine, you set them up stiff for a load and then they are fine loaded or unloaded as the suspension stays the same.

Others will no doubt chime in.  All the best in the New Year.

Thanks for the input and Happy New Year to you.

I run the 195/60R16 car tire on the rear of my bike at 42 PSI. Seems to provide the best wear ,ride and traction.  The sidecar also has a car tire.

This is by no means prefect. But it may help in figuring out air pressure. Called a chalk test. Run a line of chalk across the tire tread roll it over a clean cement floor.drive way look at the contact points.  If most of the contact is center you may be running to much air. Little center contact most on the edges maybe not enough. fairly even and fading on the very out side you may be very close to prefect. Few pounds up or down can make a major difference in some cases. Type of Car tire can also effect it. Run flats have stiffer sidewalls. Fuel save type tire have soft sidewalls.