Tubed tyres losing pressure quicker than tubeless?

[jrvip1]

I have had my Classic now for 4 weeks and each week have checked the pressures. Each week appears to lose around 2psi front and rear which leads me to think it is a trait of tubed tyres. My last bikes, R1200ST and before that R1150R which had tubeless did not lose as much pressure.

Has anyone else had similar experiences with tubeless? One advantage is that I now check the pressures regularly whereas previously I did not.

jrvip1

[deilenberger]

Chances are - you're losing the 2PSI or so by checking the pressure. Due to the small volume of motorcycle tires, it doesn't take a lot of air loss to drop the pressure a few PSI. A little "phttt" when you put the gage on is enough.

I run a tire-pressure-monitor system that doesn't require me to "check the pressure" - it checks continually, and reads out the pressure/temperature on a display. Although I have tubeless vs your tube tire - I see VERY little any continual air loss... I can go months without adjusting the pressure.

[sky_sailor]

Don's most likely bang on. I check tyre pressure about once a month. It's always down 1-2 pounds. I'll check before a trip...again 1-2 pounds, no more, no less. It's definitely lost during the check. I'll over inflate sometimes by 2#...that way, when I check it, it's bang on!
If you're going to have a "leak" with a tube, ALL the air would be gone....don't think tubes can "leak"....tubeless, you can get leaks at the rim? A valve stem problem would be the same on both types of tyres, I would think.
And, Happy Easter to all.
Lyle

[mogu83]

In my limited experience I've found that natural rubber tubes (the more expensive ones) tend to bleed off some air while the cheaper Butyl rubber ones are almost leak proof. Good tubeless tires seem to be totally leakproof.
Big plus with the natural rubber is when punctured by something, the natural rubber tube usually doesn't rip and it can be repaired with a standard bicycle tube patching kit found in gas stations and convenience stores.. The butyl tube on the other hand will some times rip even when punctured by a small nail, making repair impossible, and the patches and glue found in the standard tube patch kit many times won't stick to a butyl tube.

If I can't mount tubeless tires then I go for the more expensive natural rubber tubes and just keep an eye on the air pressure.

Naturally IMHO

[jrvip1]

That's a really interesting reply thanks. Do you happen to know which type of tube is used with a new Classic? Is it worth carrying around a spare tube as well as a puncture kit in case of punctures like I do when I go cycling?

[hjsbmw]

Chances are - you're losing the 2PSI or so by checking the pressure. Due to the small volume of motorcycle tires, it doesn't take a lot of air loss to drop the pressure a few PSI. A little "phttt" when you put the gage on is enough.

That should be easily proven or busted. Just check your pressure, take off the gauge, then recheck it. The difference tells you the loss per check. If you want to be scientific you'd have to do it a few times, each time starting at the same initial pressure, and take the average.

[mogu83]

That's a really interesting reply thanks. Do you happen to know which type of tube is used with a new Classic? Is it worth carrying around a spare tube as well as a puncture kit in case of punctures like I do when I go cycling?

Don't know which tube BMW uses but I assume its natural rubber as that's what most of the premium tubes are made of. As far as carrying a spare tube -- that's your call. I carry a spare on my /5, but a 400/18 tire (tyre for you) is a lot easier to open up on the side of the road than a 180/17, especially one with hardly any step in the center of the rim.

It would be interesting to know how owners of Classic Models plan to handle the inevitable flat tire.

[AlexGill]

I too have a R1200R Classic (2011) DOHC with the spoke wheels - I always find my tyre pressure is down when checking the tyre pressure at the filling station!

[deilenberger]

I too have a R1200R Classic (2011) DOHC with the spoke wheels - I always find my tyre pressure is down when checking the tyre pressure at the filling station!

Are you checking warm tires? Ones you've ridden to the filling station?

If so - the readings could be all over the place depending on the temperature of the air in the tire. My tire monitor not only does pressure, it also does temperature (of the air in the tire)..

Correctly filled at 70F (21C) - which is where the pressure is spec'd to:

32 front, 36 rear

At 50F there is roughly a 2PSI drop in pressure. At 90F - roughly a 3PSI increase in pressure. This doesn't seem entirely linear - which is why it's important to check pressure at 70F - or at least at the same tire temperature each time.

[Catchina]

I too have a R1200R Classic (2011) DOHC with the spoke wheels - I always find my tyre pressure is down when checking the tyre pressure at the filling station!

Are you checking warm tires? Ones you've ridden to the filling station?

If so - the readings could be all over the place depending on the temperature of the air in the tire. My tire monitor not only does pressure, it also does temperature (of the air in the tire)..

Correctly filled at 70F (21C) - which is where the pressure is spec'd to:

32 front, 36 rear

At 50F there is roughly a 2PSI drop in pressure. At 90F - roughly a 3PSI increase in pressure. This doesn't seem entirely linear - which is why it's important to check pressure at 70F - or at least at the same tire temperature each time.

The spec for my 2011 r12r is 36 front and 42 rear. Is that because I have tubeless tires, not the classic edition?

[jrvip1]

I always check the tyres cold

[deilenberger]

The spec for my 2011 r12r is 36 front and 42 rear. Is that because I have tubeless tires, not the classic edition?

Dunno - I can't imagine why yours would be different then all the other tubeless tire pressures. Are you sure you're reading the correct line on the chart? IIRC - that pressure is for "Fully loaded" (-ie - fat lady on the back and all your camping gear, ie - GVW..)

[deilenberger]

I always check the tyres cold

That's good - but there is "cold" and then there is "cold" - checking them at 40F will result in 3-4 PSI lower pressure then when you filled and checked them at 70F. Worth taking into account. The BMW tire-pressure-monitor "compensates" for this change in pressure by always displaying what the pressure WOULD be if the tire was checked at 20C (72F?)..

[KMalo]

The spec for my 2011 r12r is 36 front and 42 rear. Is that because I have tubeless tires, not the classic edition?

Dunno - I can't imagine why yours would be different then all the other tubeless tire pressures. Are you sure you're reading the correct line on the chart? IIRC - that pressure is for "Fully loaded" (-ie - fat lady on the back and all your camping gear, ie - GVW..)

I have the same 36/42 recommendation for my 2011 with tubeless tires/alloy wheels -- regardless of load. The delivering dealer took great pains to emphasize same.

Just for grins, I went down to the garage and took a look at the label under my seat -- yep, 36/42 regardless of load!

I agree with you, Don, I can't imagine why this should be but there it is.

Chuck

[ammolab]

There is no more "fully loaded" tire pressure or even a real "chart" in recent R1200R owner manuals.

Just the 36psi/front, 42PSI/rear recomendations. They just list pressures for fully loaded 2 up conditions to cover their butts for any and all situations.
This is so they don't loose a law suit from a forgetfull owner who uses the 'normal' air pressure for a fully loaded, 2up, high speed run.

[deilenberger]

You might want to try 32/36. Tires warm up faster, and the ride quality is better. Lots of people like to add pressure to a tire in excess of what actually is needed - and ride quality is the first thing to suffer.

[ammolab]

You might want to try 32/36. Tires warm up faster, and the ride quality is better. Lots of people like to add pressure to a tire in excess of what actually is needed - and ride quality is the first thing to suffer.

Yep, I ride solo most of the time and run pressures like you suggest. Only trying to explain the new limited recomendation in the manual.

[Catchina]

Interesting, so even though the owners manual, under the seat and the dealer all say 36/42 the recommendation is to go lower? If so should I try 32/38 instead of 32/36 just to evenly decrease the psi by 4 on each tire? Are there any safety issues running the psi lower then recommended?

[waynemathews]

Interesting, so even though the owners manual, under the seat and the dealer all say 36/42 the recommendation is to go lower? If so should I try 32/38 instead of 32/36 just to evenly decrease the psi by 4 on each tire? Are there any safety issues running the psi lower then recommended?

My 2009 repair manual lists this information:
36 32 - Tyres
Tyre designation, front
120 / 70 ZR 17
Tyre pressure, front
one-up, tyre cold 2.2 bar (32 psi)
two-up and/or with luggage, tyre cold 2.5 bar (36 psi)

Tyre designation, rear
180 / 55 ZR 17
Tyre pressure, rear
one-up, tyre cold 2.5 bar (36 psi)
two-up and/or with luggage, tyre cold 2.9 bar (42 psi)

I'd agree with others above is that the lawyers assume that no one checks their tire pressures and so they did away with the one-up pressure, or Americans are too fat and always overload their bikes.