Tubed or Tubeless

[marcmax]

Don't want to rehash the entire tubed or tubeless debate but I had a very weird experience yesterday. I have always run my LS wheels tubeless and have never had a problem. Yesterday I rode to see my daughter at school and take her to lunch. Nice weather, mid to high 90's, and about 200 miles of mixed freeway and secondary roads. All went well until I pulled into my daughter's driveway. I put down the sidestand, unmounted and just as I pulled off my helmet I heard a loud pfffffftt and the rear tire went completely flat. My first thought was I had picked up a nail or some other road debris and being 200 miles from home this was not going to be a good afternoon. Put it on the center stand and checked every inch of the tire and found nothing. I took my daughters bicycle pump and put enough air in the tire to make a slow trip to the nearest service station filled it to the correct pressure. Rode around the neighborhood for 15-20 minutes and all was well. Parked the bike for a few hours and it was still at the right pressure. Started home with this nagging concern in the back of my head but had an uneventful trip. This morning the tire is still at the correct pressure. Any ideas or comments?

[Julio A.]

I also run tubeless without any event but If I were you, I'd find the source of that leak before I ride out again. I Wouldn't want that to happen at speed. The first place I'd check is the Fill valve, mine once got a "little" misaligned and had a slow leak. Other than that, I couldn't see any place for a leak to occur without any punctures.

[Bob_Roller]

The LS wheels are a 'tubeless' design, not real sure what the difference is between them and a 'snowflake' wheel is.

A lot of owners with the LS wheels run them without tubes, your's is the first I've heard doing this .

The 'snowflake' wheels of the standard twin shock R65's, are not a tubeless design .

I know the Metzeler Lazertec tires I have on both of the R65's have tubeless molded (moulded) into the sidewall, don't know about other makes or models of tires .

[nhmaf]

+1 with Bob.. I'd be suspicious of the valve stem for sudden and total loss of air like that.   Be sure to push the stem around in various directions to see if it is slit near the base or not seating right.

Even if the LS rims have sufficient ridge on them to prevent the tire from slipping off - necessary for tubeless use - I still run tubes in mine.

[marcmax]

All good ideas but I am still at a loss. The valves in the rim are not standard. They consist of a rubber grommet in the rim hole and a solid metal valve stem that is pressed through the grommet and a shoulder washer and nut threaded down from the outside. There is no side to side movement. I even sprayed a soapy water mixture on the valve and tried to move it to see if I got any bubbles. None. I use metal nut valve caps that are o-ring sealed and wrench tightened so I know it didn't come out the valve itself. This was a catastrophic release of air, inflated to flat in 2-3 seconds not a slow leak. The only thing I can come up with it being a hot day, hot pavement, the tire pressure increased and the tire was soft. One of the beads may have had a marginal seat on the rim and the increase pushed it off enough for the air to release. The tires are Bridgestone BT-45's with only 800+ miles on them. I will say that there was a nice twisty stretch leading up to my daughter's neighborhood and I was flogging it pretty good. Came close to scraping the valve covers in a few corners. Scary to think of the consequences if the air pressure had released in one of those corners.

[Bob_Roller]

Now that you mentioned that the tire was recently installed, I wonder if the tire was properly seated on the wheel .

I've had two tires that weren't seated properly, I got an odd vibration from them, both were rear tires .

There should be a 'serrated' guide mark band on the sidewall, see if it is showing equally all around the tire .

[marcmax]

Checked the rear tire again today and it is still holding at the correct pressure. I did check the tire to see if it was equally spaced around the entire wheel per Bob's suggestion. It is now but I can't say for sure it was before this incident happened. I will note that I didn't have any unusual vibrations or uneven feeling from the rear when riding and I have had these tires on for a few months now.

[darrylri]

My old 1985 R80 had the LS style wheels (think they're the same as on the K75s of the era, too).  I once hit a rock with the front wheel and put a slight "wow" in it, but never felt anything in the handling, and it seemed to hold air fine... But after that, I noticed that about every 2-3 weeks, the tire would be down a few psi; and if I didn't get around to airing it up again right away, it would suddenly be down 10 psi.  

I think that the tire would "burp" just a bit of air anytime it hit a road surface irregularity when it came right at the wow in the wheel;  and when the tire pressure was down enough, it would burp quite a lot of air.

Eventually I got tired of dealing with it and bought a new wheel, which definitely solved the problem.

[marcmax]

Thanks Darryl. I have been concentrating so much on the tire itself that I didn't even think to check the wheel. Have to give it a close inspection and see if I find anything that looks not quite right.

[marcmax]

Just wanted to update on this. Since this originally happened I have checked the tire pressure each morning whether I was going to ride or not. It didn't lose a pound. Numerous trips around town and never had another instance of losing tire pressure and just assumed it was a fluke the first time. This past weekend I rode an out of town trip of approx 180 miles. No problems during the trip, while parked for lunch, etc. Got back home and was about three blocks from home and the tire pressure let go while riding. Luckily it was slow, in town riding and there was a service station nearby so I rolled in and refilled it and rode home. It has been at a constant pressure ever since. Tubes are being installed this weekend.

Just as a thought...I had Metzlers mounted the same way for the last two years (tubeless) and never had this problem. I switched to Bridgestone BT45's on the last tire change. Is it possible the Bridgestones are softer, different size, different bead, etc. that is causing it to let go and release the tire pressure?

[Bob_Roller]

I didn't see this in this thread, are the tires tube or tubeless type ?

[nhmaf]

If they are BT45 tires, I believe that they are only tubeless versions.   But, that doesn't mean you cannot run tubes in them.   I don't know about the stiffness of the  sidewalls compared to the Metzlers, but the tread compound is definitely softer/stickier, from my own experiences.

I think that adding tubes in light of your 2 pressure loss experiences is a very prudent thing to do.

[kenlodge]

nhmaf - agreed.  
that's what i did after many a ride home where i'd lose air.   but it happened infrequently enough where it didn't seem like much of an issue.  (maybe once a month or every other month).
when i got a tube put in my rear Metzler this summer, i was told that whoever installed the tire used a valve stem made for tubes on a tubeless tire.  
idk, that's what they said.  
anyhow...it holds air now, & i don't have to worry so much about getting squirrely with a flat tire on the highway.  

[montmil]

when i got a tube put in my rear Metzler this summer, i was told that whoever installed the tire used a valve stem made for tubes on a tubeless tire.

Not possible. Somebody was yanking your chain...

Inner tubes have the valve stem manufactured in place on the inner tube itself.

Tubeless installations have an entirely different valve stem secured to the rim, as no tube is fitted in the tire.

Monte

[marcmax]

Just as an FYI the riddle of my loss of tire pressure has been solved. When I had the tires removed to install tubes I decided to give the wheels a close inspection. Didn't need to. Even I could see the bit of old tire bead still stuck to the inside of the rim right where the new tire bead had to seat. About an inch long and not very thick but enough to stop a good seal. I am amazed that it held air for as long as it did. It is long gone now but there are now tubes installed as well.