Sidecar Pressure

[bostonmish]

A couple of days ago I got around to checking and adjusting the tire pressures in my /2 R90 TR500 rig. Somewhere I downloaded a BMW service advisory, from the '60s, with tire pressure recommendations.

For one up riding, the front gets 24 PSI. The rear and the sidecar are each at 27 PSI.

Upon checking, my front was too high, the rear close and the rig, too low.

I adjusted and went for a ride. ...I had a brand new bike, it seemed. So well behaved, so road holding, so nicely sprung! Now, every ride reconfirms the impression. BMW really does know its tire pressures!!!

 

[Na Cl K9]

I'll have to give that a try. Always interested in improving things...I have tended towards slightly higher pressures with no particular reason except I use the same PSI on my solo machines and figured it was good to go. That was some fairly obscure information on early factory sidecar operational specifications. I bet they are listed in my R50/2 ownerÔÇÖs book too and I've missed that all these years...Thanks for the heads up...
Thinking out loud now:
If those specs were for a single rider, do you suppose there are different specs when you have the sidecar full of kids / cargo and a passenger on back? How do you suppose those tire pressures correspond to today's modern tires and the higher performance engines that are stuffed into the old frames? An R100/7 motor has half again more ponies of an R69S and a 40mm 77RS motor would almost double the output to the rear wheel. It does sound like a sort of "bench mark" for stability though.

 

[bostonmish]

I am attaching the key excerpt from the BMW bulletin with this message.

If anyone needs the PDF of the complete original, it's here:

http://www.honda305.com/BMW/Slash2_Rig/TirePressure.htm

---

I am not sure whether modern tires need different pressures. They might, although my experince with tires is limited.

The original BMW recommendations set an official baseline on which to build (or not). I will certainly experiment with other pressures ...curious to see what happens.

--
Michael Stoic

 

[grafikfeat]

I am attaching the key excerpt from the BMW bulletin with this message.

If anyone needs the PDF of the complete original, it's here:

http://www.honda305.com/BMW/Slash2_Rig/TirePressure.htm

---

I am not sure whether modern tires need different pressures. They might, although my experince with tires is limited.

The original BMW recommendations set an official baseline on which to build (or not). I will certainly experiment with other pressures ...curious to see what happens.

--
Michael Stoic

That's what I was talking about when I mentioned a wishful desire for BMW to get back into sidecar support in another thread.
That info helps a lotta folks.
Thanks for posting it!

 

[BEEMERCHEF]

I go as high as 40 all aroud when I know I am going to be and black top all day and night. Off road I drop it all to about 24. I have an actuator on the car so road camber is never a problem just in case you have tried to adjust the angke a bit with air pressure.
The most important fact are the spings on the bike. Keep in mind that 60% of the car tongue weight is on the bike, out of that 60 % is on the rear wheel. I changed my Ohlin springs to about a 600lb rider... Handles great. One reason however to really drop that pressure when off road.
Be well... Ara & Spirit