Had a tire go down this morning! In MN here we had a cold snap down to 55f

[neoneddy]

So I was replacing the V band clamp on the turbo. Once I got it cinched down I fired it up the engine.

As it was airing up I noticed the tag axel tire was close to empty. 

Great to find that out in the driveway! I have spares here, I'm good there.

My question is could the cold snap we had going from 80s to 50s cause something to happen?

Within the last week I had checked all tires at 100~ psi, I had not driven since then.

Anyone had anything like this happen?


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[Dave5Cs]

Lots of things could be a factor. Not centered when mounted and bead not seated correctly. Mine was down to 50lbs once. did not drive on it. I took it off and had it remounted and have not had the problem since.

[luvrbus]

When you checked it the valve stem valve did not seat completely would be a guess,happens to me all the time on my tractor  

[Zephod]

When you checked it the valve stem valve did not seat completely would be a guess,happens to me all the time on my tractor  

A faulty valve core could also be the problem. Easy enough to change a valve core.


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[belfert]

I have had a bus in Minnesota for 11 years now and never had a bus tire go flat that didn't have an actual leak in it.  I almost certain that temperature had nothing to do with it.

[gumpy]

Do your tires have Equal powder in them?  I concur that it's probably the valve stem leaking.

[Fred Mc]

I remember from a LONG time ago that whenever I had air put in at a tire shop the tech. would alway put some spit on his finger an rub in on the valve stem to make sure it didn't leak.

[eagle19952]

do you have balance sand (i call it)...it can defeat a bead seat or a valve core...i hate that stuff 

[buswarrior]

Old time tire techs told me:

The cap holds the air, the valve is to keep the air in while you install the cap.

Proudly go buy metal valve caps, with the proper grommets in them.

Plastic caps are trash.

No more "leaks from the valve"

happy coaching!
buswarrior

[windtrader]

Well, that makes it worth the PIA it is to unscrew/screw that cap every time to check the air pressure. I have had the valve get partially stuck and leak some air. Push on it to get it seat itself and all good, especially with the metal air cap screwed down. LOL

[neoneddy]

Thanks everyone.

The idea that it was the valve not reseating makes sense.

I put in some air today and now tonight it's still holding fine.

Also great advice on the metal caps and spit. I'll make sure to get ones all around.

Also a TPMS is in my future ASAP

[J_E]

A general rule of thumb for automotive tires (cars, SUVs and pickups) not filled with nitrogen is -1 psig/month and -1 psig/-10*F.  Not sure how accurate the -1 psig/month works for the higher ply count tires that our coaches use.  Nitrogen may react similarly to temperature changes, but I'm not sure that it's relevant here. 

So if I air my tires up to 100 psig in May and it's 80F outside and I checked pressure in August with it also being 80F, then I would expect to see ~97 psig.  If I aired up yesterday and it's 80F and I check this morning at 50F, then I would also expect to see ~97 psig.

Elevation change, will also have an effect, but I do not know if there is a thumb rule.  A quick check on Google says a typical atmospheric pressure in Denver is 12 psia and at sea level it's accepted as 14.7 psia.  (PSIA because PSIG would read 0 psi at both locations)  So 100 psig @80F in Denver would read about 97 psig @80F in New Orleans.  In reality, the temperature change between New Orleans and Denver would typically offset the pressure change due to the altitude change.

Does anyone run an aftermarket TPMS on their bus/coach?  I had a tag tire that had begun to come apart and only noticed it because I saw something black fly through my field of view in my side view mirrors and I didn't hear or feel anything.  Some sort of alarm might've allowed me to save the tire or at least made sure that I was aware of an issue.

[Zephod]

TPMS is only good if it doesn't run off a non replaceable battery. The TPMS in my car is worthless. That's why I've never replaced the sensors that die. All it did was light up an amber light on the dash and make a screeching noise. It never told me which tyre was the problem nor the pressure in any of them. When I get my next tyre change (been on these for 7 years), I'll get them to replace the TPMS valves with ordinary valves. Most of them don't work now and at $100 each they're not worth replacing. When they worked,  would alert me to low pressure half an hour after I started driving. Slightly less useful than a chocolate teapot.

I have seen good TPMS systems that give the pressure in every tyre. Now those look worthwhile.




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[J_E]

I have seen aftermarket systems for cars that give the tire pressure and have an alarm that can be set.  I would imagine that a similar system exists for trucks that will also work on buses.  These aftermarket systems use a transmitter that installs in place of the cap on the valve stem.

Having only a light and a buzzer is better than hoping that you notice something in the mirrors or can feel the difference in the steering.

[Zephod]

I have seen aftermarket systems for cars that give the tire pressure and have an alarm that can be set.  I would imagine that a similar system exists for trucks that will also work on buses.  These aftermarket systems use a transmitter that installs in place of the cap on the valve stem.

Having only a light and a buzzer is better than hoping that you notice something in the mirrors or can feel the difference in the steering.

Nothing beats a pre trip inspection though.


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