inner tubes question

[MooN]

 Do modern innertubes eventually go pourous?  how often are you supposed to replace them? 

I'm having a bit of an odd phenomenon with mine at the moment.  

The tiger has spked wheels, so runs tubes. they're fitted in "tubeless" tyres ( pirelli scorpion III) and have been without problem untill this summer.

With the temperature range having been larger then usual this summer I have expected a certain amount of pressure variation but have been finding that both front and rear tyres need systematically pumping up, and always the same amount. the rear ( officially running at 2.9kilos pressure) will be missing 0.4K when I check with cold tyres wether they've been let overnight or for a number of days, The front ( usually at 2.5kilos) will be missing 0.2kilos. This has been the same EVERY time I check tyre pressures, which has been every time I ride cos I know they'll be low)

I use a pressure guage to check the pressures and then a foot pump with a manometer on to pump them up. Both guages correspond. I have found no leak at the valves ( and anyway, if it was a valve leak it would surely continue leaking, not just drop the pressure by 2 or 400 grammes respectively... and to have BOTH valves go dodgy at the same moment...! Unlikely in the extreme I would imagine. 

So, my next thought is " Pourous tubes". is that still a thing with modern rubber?  I ran tubes on the transalp too so have been using them for 20 odd years and never suffered from it before.  

Any other explanation?

Just to throw out any theories you may come up with, I corrected the pressures on saturday morning befor leaving for a weekend trip. Over the weekend did 800 and odd km's getting home sunday night.  Checked tyre pressures monday morning and they were spot on, not lost a gram! and yet they've systematically lost pressure overnight for the last few months. 

[XTreme]

[Buckster]

Yes they do eventually, you should always get the best quality tubes you can find.

[Sir Fallsalot]

Its normally recommended you fit a new tube with every new tyre 

[Pedro]

40 minutes ago, MooN said:

 Do modern innertubes eventually go pourous?  how often are you supposed to replace them? 

I'm having a bit of an odd phenomenon with mine at the moment.  

The tiger has spked wheels, so runs tubes. they're fitted in "tubeless" tyres ( pirelli scorpion III) and have been without problem untill this summer.

With the temperature range having been larger then usual this summer I have expected a certain amount of pressure variation but have been finding that both front and rear tyres need systematically pumping up, and always the same amount. the rear ( officially running at 2.9kilos pressure) will be missing 0.4K when I check with cold tyres wether they've been let overnight or for a number of days, The front ( usually at 2.5kilos) will be missing 0.2kilos. This has been the same EVERY time I check tyre pressures, which has been every time I ride cos I know they'll be low)

I use a pressure guage to check the pressures and then a foot pump with a manometer on to pump them up. Both guages correspond. I have found no leak at the valves ( and anyway, if it was a valve leak it would surely continue leaking, not just drop the pressure by 2 or 400 grammes respectively... and to have BOTH valves go dodgy at the same moment...! Unlikely in the extreme I would imagine. 

So, my next thought is " Pourous tubes". is that still a thing with modern rubber?  I ran tubes on the transalp too so have been using them for 20 odd years and never suffered from it before.  

Any other explanation?

Just to throw out any theories you may come up with, I corrected the pressures on saturday morning befor leaving for a weekend trip. Over the weekend did 800 and odd km's getting home sunday night.  Checked tyre pressures monday morning and they were spot on, not lost a gram! and yet they've systematically lost pressure overnight for the last few months. 

Loosing pressure overnight between end of day and morning might just be the difference in ambient temperature cooling the tire enough that air inside doesn’t expand as much as when you measured it after a day of warmth. Did you check if they would go back up at the end of the day?

Check them the day after at the time and ambient temperature you’ll ride.

Cold temperatures in tires means ambient temperatures before you ride. 

[yen_powell]

My pressures change with the weather, not just air temperature, but air pressure as well. This usually shows as both front and rear changing at the same time with a bigger change on the front which has a smaller volume. If I am always pumping the same one up then it is usually a valve (or rim problem for tubeless).

BUT, I have had a few tubes rust where the valve joins the rubber part and then leak very slowly there.

[MooN]

should I be replacing tubes periodically? I never did on the tralp, I had the same tubes for years.

[Buckster]

1 hour ago, MooN said:

should I be replacing tubes periodically? I never did on the tralp, I had the same tubes for years.

With every new tyre is the norm. 

[MooN]

13 minutes ago, Buckster said:

With every new tyre is the norm. 

Really?  Wow, never done that. the tubes I have in must be 4 or 5 years old... 

[busabeast]

Never had a bike other than bicycle that had tubed tyres so I can't help, though it does seem to point towards porous tubes or the valve connection is corroded but I'd expect them to go flat rather than just lose a small amount of pressure over night.

I'd replace the tubes as due course to rule out a set of dodgy tubes im sure they are easy enough to get changed and cheap enough 

[yen_powell]

I used to put new ones in with each tyre change on my AT and keep the one removed as a spare for puncture replacement rather than patching the tube that was damaged. That way my spare was only slightly older than the one in the tyre.

[boboneleg]

What @Pedro and @yen_powell said about temperatures

Modern tubes have a lot of butyl , much more than the natural rubber tubes we used to use years ago.  How old are your tubes , are they the o/e tubes that came with the bike or has a previous owner replaced them with cheap shite ?

As @Buckster said, buy the best tubes you can.  I nearly always try to use Michelin tubes (personal choice) as they work well for me .

[MooN]

I'll keep an eye on pressures for the moment and plan to change the tubes with the next tyre change I guess. My problem with that is that there is absolutely no trustworthy motorcycle mechanics within a 100km radius of here so any tube change is going to involve some organisation. 

[Pedro]

1 hour ago, MooN said:

I'll keep an eye on pressures for the moment and plan to change the tubes with the next tyre change I guess. My problem with that is that there is absolutely no trustworthy motorcycle mechanics within a 100km radius of here so any tube change is going to involve some organisation. 

How many km do you ride to have your tires replaced, usually?

[MooN]

4 hours ago, Pedro said:

How many km do you ride to have your tires replaced, usually?

Not really taken that much notice to be honest Pedro, when they look worn i change them. I rarely change front and rear at the same time. Ive done about 50,000km on the tiger and dont thing ive changed tubes.

[Pedro]

Just now, MooN said:

Not really taken that much notice to be honest Pedro, when they look worn i change them. I rarely change front and rear at the same time. Ive done about 50,000km on the tiger and dont thing ive changed tubes.

No, I meant how far away to go to have them replaced, like distance from home to your usual tire shop.

[MooN]

11 minutes ago, Pedro said:

No, I meant how far away to go to have them replaced, like distance from home to your usual tire shop.

Sorry i misunderstood.

bout an hour and a half, or 2 h if not on the autoroute, 140odd km i suppose. 

[XTreme]

2 hours ago, MooN said:

Ive done about 50,000km on the tiger and dont thing ive changed tubes.

That many?

What's it done in total then?

[boboneleg]

5 hours ago, MooN said:

Sorry i misunderstood.

bout an hour and a half, or 2 h if not on the autoroute, 140odd km i suppose. 

So when you need new tyres you take your bike to a Motorcycle dealer/repair shop  ?

[Pedro]

24 minutes ago, boboneleg said:

So when you need new tyres you take your bike to a Motorcycle dealer/repair shop  ?

Should he take it to a barber?

I take mine to my mechanic or to a tire shop I’ve used for ages, they do bikes, cars, vans and trucks, alignment there works for anything from a 3 ton Iveco to an F3 racecar

140 km does seem like a lot to me, I do 30

[XTreme]

27 minutes ago, Pedro said:

Should he take it to a barber?

[boboneleg]

46 minutes ago, Pedro said:

take mine to my mechanic or to a tire shop I’ve used for ages, they do bikes, cars, vans and trucks, alignment there works for anything from a 3 ton Iveco to an F3 racecar

That was the point I was trying to make @Pedro  Most people here would use a tyre shop rather than go to a motorcycle dealer.  Motorcycle shops here are generally not interested in fitting tyres.

I fit my own but in the past when I have used a tyre shop I generally take the wheel off myself and then let them fit the tyre/tube.

[Pedro]

1 minute ago, boboneleg said:

That was the point I was trying to make @Pedro  Most people here would use a tyre shop rather than go to a motorcycle dealer.  Motorcycle shops here are generally not interested in fitting tyres.

I fit my own but in the past when I have used a tyre shop I generally take the wheel off myself and then let them fit the tyre/tube.

For the record, here, the BMW dealership where I bought my bike would charge me only 20 to 30€ more to sell and fit the same pair of 300€ Heidenaus my tire shop did. That’s with new valves and balancing.

I have used another BMW dealership out of convenience, and the same difference applies, I know some people cry for every euro but to me that’s very reasonable.