Tyre FAQ

28 February 2009

Talk about tyre pressures, tubes, rim locks and puncture repairs.


Wheel Specs:

Rim, front 2.15 x 21"
Rim, rear 4.25 x 17"

Tyres, front 90/90 - 21 54V
Tyres, rear 150/70 - 17 69V



What pressures should I run my tyres at?


For stock tyres:

FRONT one-up: 2.2bar/32psi at 20 degrees celcius
FRONT two-up and/or with luggage: 2.5bar/36psi at 20 degrees celcius

REAR one-up: 2.5bar/36psi at 20 degrees celcius
REAR two-up and/or with luggage: 2.9bar/42psi at 20 degrees celcius

A quick internet search will throw up correct pressures for alternative tyres. 2.2front/2.5rear seems to be common. On the road I quite liked 2.5front/2.9rear only one-up on the stock Battlewings.



Can I use Tubeless Tyres on the 800GS?

Yes, Tubeless tyres (TL) are fine. So are tube-type (TT) tyres. See Chart above. But either way you will still need a tube (see rim sizes above).

That's because the wheels have spokes and air will leak out if you don't have a tube. The 1200GS has special spoke that go to the side of the wheel so their owners can use tubeless tyres - you can't on your 800GS.



Do I need Rim Locks?

Probably not, unless you're planning to do the Paris-Dakar on the 800GS in which case you should know a lot more about tyres and tubes already.



How do I check pressures at 20 degrees celcius?

Set the climate control in your garage to 20 degrees celcius and only ever check your pressure in there.

OR...bear in mind that a change of 10 degrees celcius is equivalent to a change of about 0.07bars or 1psi. So on a near freezing day increase pressure by about 0.14bars/2psi or on a very hot Death Valley kind of day reduce pressure by 0.14bars/2psi. This applies to 'cold' tyres that haven't been ridden on recently, I have no idea how hot your tyres will be after a few trails.



Should I reduce pressures when off-roading?

If you're going on sand, gravel or very gloopy mud you can maybe lose 5psi/0.4bars but much less and you risk 'tyre slip' where the wheel spins but the tyre doesn't. This will result in the tube valve being ripped out and sudden deflation. You could deflate more and use rim locks (see above).

Put it this way: the BMW Off-Road schools runs their 800GSs off road at road pressures. 'nuff said.





If I want to repair a puncture out on the trails, what tools will I need?



  • 22mm socket for front axel

  • 24mm socket for rear axel

  • a wrench for the sockets

  • Torx keys for M8 and M10 torx bolts (front axel clamps and front brake calliper)

  • Tork key for the ABS sensor if you are clumsy and might knock it when removing/replacing wheel

  • A centre stand (or lie the bike down)

  • A large rock/block to go under the engine when you want to remove the front wheel on the centre stand (or lie the bike down)

  • Tyre levers (two or three, depends how good you are)

  • Rim protectors or bits of plastic bottle (so you don't scratch the rims, depends how precious about your bike you are)

  • A bead breaker (or thick heavy boot heal)

  • Some 4"X4" or something to rest the wheel rim on while you break the bead with your boot, or you will knacker the sprocket/brake discs. Or you can dig a hole in the dirt.

  • Valve removal tool (to take the valve out of the valve stem to deflate the tube enough to get it out)

  • A little spanner (wrench) to remove the lock nut on the valve stem

  • A puncture repair kit (patches/glue) or a spare tube

  • A inflation device (CO2 cartridges, electric compressor or hand pump)

  • Some prior knowledge of how to repair a puncture. Best to practice at home before you need to do it for real.

Good grief thats a lot of stuff for a puncture? Isn't there any easier way?

Yeah. Push bike to nearest road. Phone BMW assist.



Har Har. Can't I just plug the tyre?

No, its got a tube, remember? Should have bought the 650GS.



What about tyre sealant? Can I use that?

Bit late once you have a puncture. There are special formula sealants for tubed tyres. Messy stuff though, and it won't work on gashes or big punctures, but it will gloop everything up and make the tube irrepairable. Also, a small nail in the tyre can cause a large rip in the tube as the tube 'squirms' inside the tyre at speed.


Any other advice?

Practice repairing punctures at home, until you are confident about removing wheels and tyres. Learn how to fix these things in your garage at home when its easy to get help. Once it is second nature, out on the trails it won't be an issue for you.

Oh, and make sure your riding partner has a spare inner tube also. If he gets a puncture and takes your spare, you can guarantee you will get a puncture a mile later. And you can guarantee he won't take your spare off his wheel now...



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About This Blog

I had been saving for a ST1300 for a long time, as it was clear that my Deauville wasn't up the task.

In November 2007 I saw pictures of the F800GS and ran to the dealers to place a deposit.

On 13th March 2008 I took delivery and have never regretted it.

On 13th April 2009 my 800GS joined me in Singapore for a new life and adventures...

This is my F800GS Blog.

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