Riding in thick sand
The problem with letting air out of the tyres for riding in thick sand is that the tyre beads often unseat and the rim can spin inside the tyre.
One fix I've heard of is to drill four holes in the rim, two each side, at 90 degrees to each other and then use a self-tapping screw to bite into the tyre. Anyone tried this?
What size screw should be used?
Finally, what's a good pressure to maintain in the tyres for sand riding?
I have many years ago used self tapping metal screws with a flat cap to screw into the side of the rims and into the tyre. I remember using 6 per side whilst a friend used 3 per side. I don't think there was much difference, if any.
What you have to do is measure the thickness of your rim and also the thickness of your tyre bead and ensure that you don't go through to puncture the tube.
Another way out is to buy tyre rim fix. This is a product from Rema that helps to bond the tyre bead to the rim and in the case of badly fitting tubeless tyres helps to seal.
As for tyre pressures you have to compromise between traction and rim damage. If you are running a heavy bike, any flat twin BMW is a heavy bike, then you cannot go too low, especially on the front if you don't wish for damage in a pot hole. If there is only soft sand then you can really go quite low, especialy if you have the tyre attached to the rim as above.
Over the years I've worked out that the best overall touring pressure for my 1100GS is 2.1 Bar in the front and 2 Bar in the rear I run this pressure on paved roads and tracks to sandy tracks. I run this pressure in the TKC 80 tyres which are the knobby ones for that bike.
My R80 G/S was a little different and I ran lower pressure which was around the 1.7 Bar front and 1.5 bar in the rear. This was a tubed tyre bike and it ran well with those pressures on all surfaces.
For 16 years in between those two bikes I ran a BMW R100CS and mainly used road tyres. However when travelling on dirt or sandy tracks I ran 2 Bar front and 1.6 Bar rear this seemed to work quite well and the handling when back on a hard surface wasn't too bad. With this bike I ran straight road tyres almost all of the time. Although a few times I ran a Trials universal tyre on the front and a full knobby on the back. Unfortunately the weight of the bike did destroy the tyres if I went much over 120 Km/h so touring speed on a paved surface was close to 95 100 Km/h.
All of the above pressures were used when the bike was fully loaded and two up, you are not trying to race when touring and it really is relaxing when the bike handles reasonably well on poor roads and you are able to take in the views if they are there.
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