99 Sierra Wheels go flat

[arnard]

We have been having a problem with my Dad's 99 Sierra ever since we got the thing. Randomly the wheels go flat. It can go for days or months with no problems, then one day the tire is flat. We have had the tires off and on (at least 3 different tires have done this) numerous times and the tire shop never finds any holes (or leaks for that matter) but they pull it off then put it back on thinking that maybe the bead didn't seal. I am starting to wonder if maybe the rims leak. Is that possible? I noticed a few TSB titles at alldata that made it appear this might have been a problem with our truck.

 

Please help, this is driving me nuts and I am about to have tubes installed!

[GM-Tech]

Just fixed a porous aluminum wheel on a '06 Trailblazer right off the transport from the factory. So yeah, wheels can leak.

 

But these are typically very slow leaks. They don't suddenly go flat or go months without a problem then show up now and then. And three different tire/wheels? Sounds pretty weird to me.

[arnard]

Just fixed a porous aluminum wheel on a '06 Trailblazer right off the transport from the factory.  So yeah, wheels can leak. 

 

But these are typically very slow leaks.  They don't suddenly go flat or go months without a problem then show up now and then.  And three different tire/wheels?  Sounds pretty weird to me.

 

<{POST_SNAPBACK}>

 

 

 

Sorry to pick your brain on this.

 

How long would it take to appear? Could it have been leaking for weeks but not enough to show up?

 

Would putting tubes in the wheels fix the problem or would something else need done? Also, any idea what the TSB's are for? The titles are:

 

05-03-10-003 MAR 05 Aluminum Wheels - Low Tire Pressure Condition

03-03-10-001B AUG 04 Wheels/Tires - Tires Slowly Flatten/Wheel Vibration

03-03-10-001B AUG 04 Tires/Wheels - Tire Slowly Goes Flat/Wheel Vibration

 

The truck has the chrome plated wheels if that makes a difference. Plus it happens at his place and 20 miles away at my house so it can't be neighborhood hooligans. It has been about 2 weeks since I brought it to my house and the RR is starting to look spongy.

 

Final question, how is something like this repaired and how would you even find the leak?

[mmmikkke]

Have you owned the vehicle since it was new?

 

If not, and if the truck/wheels had been given rough treatment (high speeds over bumps, overloading, etc.) by the previous owner you might have microscopic cracks in the wheel(s) which only leak air when the wheel is parked rotated to a particular position.

 

Or if the tires have had nail holes which have been plugged, the plugs might hold air unless they're at the edge of the contact patch and the tread is flexed just right to let them leak.

 

Or a inside patch might have been done improperly...behaving the same way as the plugs.

 

I'd start by scanning the insides of all the offending tires, and replace all plugs with patches, and replace any patch that looks suspect.

 

All of this is with the assumption that the tires are a national brand and they look reasonably new.

 

I'd also check air pressure on each tire daily and keep a log. Sounds like there's more to learn about the problem.

[arnard]

Have you owned the vehicle since it was new?

 

If not, and if the truck/wheels had been given rough treatment (high speeds over bumps, overloading, etc.) by the previous owner you might have microscopic cracks in the wheel(s) which only leak air when the wheel is parked rotated to a particular position.

 

Or if the tires have had nail holes which have been plugged, the plugs might hold air unless they're at the edge of the contact patch and the tread is flexed just right to let them leak.

 

Or a inside patch might have been done improperly...behaving the same way as the plugs.

 

I'd start by scanning the insides of all the offending tires, and replace all plugs with patches, and replace any patch that looks suspect.

 

All of this is with the assumption that the tires are a national brand and they look reasonably new.

 

I'd also check air pressure on each tire daily and keep a log.  Sounds like there's more to learn about the problem.

 

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We have not had the truck since new, but when we bought it the dealer had put new tires on it. They are Cooper H/T's. The truck previous to our use was supposedly used on a farm by an older gentleman so I suppose cracks are a possibility. I can start a log and I think that is a great idea. I will also try to keep track of where the rotation of the wheels is when it is parked.

 

If it turns out the rims are cracked is it even safe to use them still?

[mmmikkke]

...If it turns out the rims are cracked is it even safe to use them still?

 

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No. It would be asking for trouble.

 

But I think it's a lot more likely that you have plugs or patches that aren't holding air, when the plug or patch is stretched just right by parking on it.

 

And there's a chance (especially if the tires are oversized) that your tires go from 50 down to 20 without showing it, and then from 20 to 10 they melt like the wicked witch of the west.

 

So it might just be slow leaks. Keeping a log will shed some light on this.

[GM-Tech]

05-03-10-003 MAR 05    Aluminum Wheels - Low Tire Pressure Condition

03-03-10-001B AUG 04    Wheels/Tires - Tires Slowly Flatten/Wheel Vibration

03-03-10-001B AUG 04    Tires/Wheels - Tire Slowly Goes Flat/Wheel Vibration

 

The first TSB is about finding and sealing porosity leaks in aluminum wheels. Actually, nothing on finding the leak. That should be easy.

 

The second TSB is...

 

Tire Slowly Goes Flat and/or Excessive Wheel Vibration Caused by Bead Splits (Replace Wheels with New Heavy Duty Rim Version) #03-03-10-001B - (Aug 2, 2004)

 

1999-2004 Chevrolet Silverado 1500 Series Pickup Models

 

2000-2004 Chevrolet Suburban, Tahoe

 

1999-2004 GMC Sierra 1500 Series Pickup Models

 

2002-2004 GMC Yukon, Yukon XL

 

With 6-Bolt, 16 X 6.5 Full Face Steel Wheel (Base and RPO PY2)

 

The third TSB you listed is identical to the second.