[JaxChris]

EDIT: Title changed due to confusion, explanation HERE

I was chatting about the new car with a coworker at lunch today and during our talk he mentioned something to me that didn't sound like bs, so I figured I'd ask those with experience if this is as logical as it sounds. I've never dealt with run-flats before.

Mentioned going to Bradenton later this year to get some drag time in with the Camaro. During the discussion I said I had read where people are saying for this size tire to bag them to around 20-25 psi. After a moment of hesitation he remembered that I previously said the car came with run-flats instead of a tire compressor. He said don't do it and get a second set of rears with more compliant sidewalls if I wanted to go to the strip.

Reason: Run-flats have a specific sidewall structure that is designed to take over when pressure falls or completely escapes. Once that happens, you have about 50-70 cruising miles on them to get to a shop. The minimum psi before the sidewalls take over (and their structure begins to compromise) is usually 26-28 psi, and should not be run below 35 psi. Bagging and launching on run-flats would kill their rigidity and would likely fail when a puncture occurs, ruining their entire purpose.

Question -- this made sense to me, what about the rest of you?

[Cdflyer]

While I don't think it will compromise the inner structure of the tire too much, I'm sure it has a slight effect, but nothing that will hurt the lifespan of the tire. Then again, having race only tires is never a bad idea.

[jdasnt3]

I haven't had any premature wear on ours. We dropped pressures to 20PSI and ran 3-4 times on four occasions. We now have 3-4K miles after doing that and the fronts are wearing the same as the rears.

That being said, we purchased DR's on rims recently and plan on running the Nitto 555R's at Bradenton from now on since I have traction issues now.

[GirlyNFG]

I dropped mine to 15psi just to see if it made any difference on the track and it didn't. I have welds and hoosiers now.

[MiamiBlueCamaro]

OP changed title of post "below picture now irrelevant"

[Norm Peterson]

Originally Posted by JaxChris

Question -- this made sense to me, what about the rest of you?

Your term "bagging" doesn't make much sense to me. Suspension air bags for adjustable ride height? Inner tubes?

But anyway, I think the point he was getting at has to do with possible fatigue effects within the sidewall cord structure. It's stiffer than with non-runflats so that the car will still be supported (to some extent, anyway) by the tire's sidewall structure (instead of the wheel's flanges).

Fatigue is a much more complicated topic than can be described by the few numbers you can find on this tire topic. Long story short, the RF tire may be rated for 50 miles @ 50 mph . . . at zero inflation pressure, where the sidewall structure isn't getting a bit of help from the air inside the tire. The higher the inflation pressure, the more help from inflation you're getting.

At any non-zero inflation pressure, RF tire distortions will be less, heat generation lower, and life longer under that condition than when the RF sidewall structure is having to do all the work.

Naturally, you wouldn't expect them last as long being run at 25 psi as they would at 35 or whatever is called for. But neither would a non-RF tire.


Norm

[SuperSound]

What size Nittos are you planning to run? Trying to figure out what would be cheaper, get a set of light weight wheels for a smaller set of DRs or get a size to work on the factory wheels.

[LesserO2Evils]

Nothing about this makes sense to me..."Bag"?????
Ive ran "low pressure" in RF tires dozens of times thru the years w/zero issues. If thats what you mean.

[Norm Peterson]

I've never heard the term 'bag' or 'bagging' used for a car other than with respect to air bags used in the suspension instead of the OE steel springs.

So if it's being used in a different sense here it's got to be some sort of slang that I've never heard before. Maybe it's only regional to the deep South???


Norm

[TransAmx2]

Originally Posted by Norm Peterson

I've never heard the term 'bag' or 'bagging' used for a car other than with respect to air bags used in the suspension instead of the OE steel springs.

So if it's being used in a different sense here it's got to be some sort of slang that I've never heard before. Maybe it's only regional to the deep South???


Norm

Central Florida here, and I agree, the term "bag or bagging" as far as I have ever know it would refer to air bag suspension, nothing to do with dropping tire pressure. Either different terminology or just some confusion on definitions on OP's part, no biggie, I still have friends I give a hard time to every time they say "Pop" for soda.

[JaxChris]

Bag -- slang term since the mid-late 90's referring to the low tire pressure warning indicator which looks like a full plastic grocery bag on a flat surface. When people let the air out of the rears when they got to the track, they were setting off the indicator or "bagging" their tires.

But if it confuses people, I will change it. =)~

[Norm Peterson]

Thanks for that. I appreciate the explanation, particularly the origin. I may never use it myself, but at least it'll really have some meaning when other people do.

One definition of a good day is a day where you learn something new.


Norm

[506JTF]

Originally Posted by JaxChris

Bag -- slang term since the mid-late 90's referring to the low tire pressure warning indicator which looks like a full plastic grocery bag on a flat surface. When people let the air out of the rears when they got to the track, they were setting off the indicator or "bagging" their tires.

But if it confuses people, I will change it. =)~

This is a common term used around here!
It's not uncommon for people to come up and ask if were "bagging down" the tires.

[Norm Peterson]

Originally Posted by 506JTF

This is a common term used around here!

One of my original points, exactly.

Regional slang usually doesn't have much meaning outside whatever region, even though it makes perfect sense to those inside it. FWIW.

I think this horse is dead now . . . maybe looks a bit - dare I say it - "bagged"?


Norm