Tyre Pressures - how to.....

[Fraggle]

I have a 1980 twinshock 65.

The valves are so close to the "spokes"  (allow snowflake pattern) on the wheels, I can't get an air line on them and have had to resort to using a foot pump with a right angled connector.

The guage on the foot pump is not really accurate. So I over inflate take the connector off (in the process loosing a bit of air) then use a pencil type pressure guage bleeding some out until I get to where I want to be.

The front tyre is a nightmare - it has a shorter valve that barely acceptrs the foot pump (I have to hold it down and pumnp with my hand)

This is time consuming and very tedious.

Anyone have any tips on how to reliably and consistently set the typre pressures or explain whats wrong?

[Bob_Roller]

Your experience is pretty much normal !!!

You're going to need to find a right angle service tool for the end of the airhose .

Same with the pressure imdicator .

I've had my '81 R65 with snowflake wheels for coming up on 37 years and it's been a pain every week when I check the pressures .

My '87 Guzzi front wheel is even more of a pain than a snow flake wheel .

[Barry]

I have a right angle connector but never use it as it's too much trouble. I always use a foot pump and check with a pencil gauge exactly as you described. 

On the front it either needs a new tube with longer stem or perhaps a lock nut(s) has been left on the stem inside the wheel rim.

[Matt Chapter]

My rear rim (I have tri-y rims on my monoshock) was a pain to inflate, and has a sloooow leak to boot.  So I added a 90 degree adapter.  I leave it on all the time, it's been on there for over 10000 miles with no adverse effects.

I use a tall bicycle pump with a built in gauge to inflate.  It's a good workout for the arms!

[Barry]

Angle adaptors  do seem to be widely used without problems but just out of curiosity I put some numbers into a centrifugal calculator to see what the impact on wheel balance would be if the wheel was balanced without the adaptor in place

The adaptor I have always felt too heavy to leave in place. I just measured it at 20 grams. I'm sure there are much lighter ones available at say 10 grams.

If we assume maximum 1300 wheel rpm (approx 100 MPH) and the adaptor weighs 10 grams  the out of balance force is  4.3 KG or 9.5 lbs.  That's a nice illustration of how important wheel balance is.

[Tony Smith]

I do not trust permanently fitted right angle adapters, I've never bothered to do the calculations but Barry's calculations bear out my gut feeling.

At home I have a chuck on my compressor that fits, but that of course doesn't help when away from home.

Go to a truck tyre place, they will have valve extension hoses meant to be used in truck dual wheels - screw onto the tyre valve and the standard garage tyre chuck will then fit - adjust pressures and then remove. Best of all they are dirt cheap.

[Rob Valdez 79 R65]

What is really laughable is trying to get the stock tire pump head on that tire valve!!!

[georgesgiralt]

Hello !
After much complaints, BMW heard us curse them and devised, in it's wisdom, a nice addition to the tool roll : 71111239258 which is a 90° valve adaptation, with one female thread at one end and a valve at the other ! This way, air do not escape when this device is fitted to the tube. It allows to measure, correct and measure and also has a cap to remove the valve is need be...
Around 19 USD apiece.... But in nice copper....