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Alloy Wheels Loosing Air

 
 
Reply Fri 26 Dec, 2008 08:25 pm
bought a honda accord in august this year . it's a fine running car withs LOTS of doodads .
one of them is the TPS (tire pressure monitoring system) . the car is shod with 17 inch alloys and michelin tires - tire pressuree 32 pounds .
when the first coldspell hit in early december : the TPS lit up !
checked tire pressure : down to 28 pounds .
phoned honda : just re-inflate and all will be fine .
inflate (in the cold) to 32 pounds - all fine .

about dec. 20 : purchased and had installed a set of michelin snows at the tire store .
instructions : please set pressure at 32 .

(later recalled that it was VERY HOT in the shop and about MINUS 15 C outside )

driving home : TPS comes on !
next day back to tire store - head scratching - mumbling - up on the hoist ...
tire store : alloy wheels have a tendency to leak - get steel rims !
drive home : TPS comes on !
next day phoned honda salesman : yes , he had heard of the light coming on in extreme cold , probably o.k.to drive , if you didn't have TPS you wouldn't have noticed , will talk to shop .
salesman calls back : yes , tire installer confirmed problems , don't worry ... ...
cannot install steel rims unless they have TPS - VERY expensive if available at all !

next day : remembered an old Mechanics Illustrated article from about 40 years ago .
feature writer UNCLE TOM (tom mccahill ?) recommended that one always put some extra air in the tires !
inflated tires to 36/37 pounds : no more TPS light coming on !

i'll still be talking to honda . doesn't seem to make any sense to have a TPS and being told to ignore it .

rechecked tirepressure and it is now holding .

anyone had a similar experience with alloys and TPS when the temperature dropped below freezing ?

does anyone use tire caps with pressure monitor ? do they work ?

http://ecx.images-amazon.com/images/I/41GXWNARGNL._SL500_AA278_.jpg








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Type: Discussion • Score: 3 • Views: 10,928 • Replies: 23
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parados
 
  1  
Reply Fri 26 Dec, 2008 10:10 pm
@hamburger,
Put air in when cold.

Air contracts when cold so your tires don't lose air, the pressure goes down because of temperature. I'm surprised the tire guys didn't know that.



Quote:
inflate (in the cold) to 32 pounds - all fine .

about dec. 20 : purchased and had installed a set of michelin snows at the tire store .
instructions : please set pressure at 32 .

(later recalled that it was VERY HOT in the shop and about MINUS 15 C outside )
0 Replies
 
Rockhead
 
  1  
Reply Fri 26 Dec, 2008 10:22 pm
@hamburger,
I got a codger friend give me some of those, never put them on, cuz they was ugly...

have you thought about using nitrogen?

http://www.getnitrogen.org/
0 Replies
 
Chumly
 
  0  
Reply Sat 27 Dec, 2008 01:40 am
Cast (that's the more correct term) is not more permeable to air than steel (which is also an alloy). The crap so-called "professionals" in the automotive world try and spew!
0 Replies
 
talk72000
 
  1  
Reply Sat 27 Dec, 2008 01:56 am
@hamburger,
Aluminum alloy probably contracts in the cold more than steel so the gap between the tire and rim is incrementally increased thus the leak. As Parados suggested fill tire with air outside using the air hose by the gas pump.
Chumly
 
  0  
Reply Sat 27 Dec, 2008 01:58 am
@talk72000,
Nope, the cast rim is more rigid that the steel rim; further the expansion coefficient as comparing cast versus steel would not be relevant given the flexibility of the tire bead.
roger
 
  1  
Reply Sat 27 Dec, 2008 02:02 am
@Chumly,
And there is no gap between the tire and the rim. If there were, it would get smaller as the wheel contracts, which is irrelevant, as there just isn't a gap.
0 Replies
 
hamburger
 
  1  
Reply Sat 27 Dec, 2008 08:54 am
hi to all !
thanks for your quick responses .
will reply individually and also let you know what ecuse honda has .

i did read on one website that alloy/cast/alu wheels require a SPECIAL sealant for proper bonding .
hbg
0 Replies
 
curtis73
 
  2  
Reply Sat 27 Dec, 2008 10:28 am
Whoa... guys... responses all over the board here.

First of all... Nitrogen won't help this problem. Nitrogen contracts its volume at the same rate as mixed air from the atmosphere. Boyle's law (PV=nrT) is the same for all gasses, nitrogen included. Nitrogen is desirable for two reasons. First, its inert and dry. It won't oxidize the inside of the tire because there is no oxygen. Second, Nitrogen is a predictably larger molecule. When you fill with atmospheric air, its 78% Nitrogen, but 1% of it is little stuff like Hydrogen, Helium, and other stuff that can leak out much faster.

Aluminum wheels are known to corrode around the bead seat. When they corrode enough, they start to leak. Its about as common as hearing about Jesus in church. Its a well-documented issue that is so easy to prevent its ridiculous. At a tire shop, if the guy pulls an old tire off an aluminum wheel and notices a little corrosion, he simply installs the new tire with a little black sealant gunk. Its not something you have to put up with, nor is it something that the tire shop can ignore. If they gave you back a car with leaking tires, they need to do it right. It doesn't matter what wheels you have. It is their job to install tires correctly on aluminum wheels. Think of the billions of aluminum wheels out there on the road today. There may be more aluminum than steel.

Also, I don't care how cold it is, it takes about 20 degees change to make a 1psi change in tire pressure. If he put 36 psi in, when its below freezing its not going to trip the light at 28 psi.... unless its about 65 below zero.

The thing you need to do is check the tire pressure when the dash light is on to determine if the sensors are faulty or if they are operating correctly. If it is trustworthy, then you have a leak. If it is just coming on everytime its cold outside, yank the dashboard, rip the bulb out of that socket, and monitor your tire pressure like everyone else does (or doesn't as I watch cars drive with flat tires every day.)

The part that REALLY chaps my ass is that the tire shop actually suggested you get steel rims because aluminum rims leak. I suggest you punch that guy in the nuts. That is the most insulting, BS, ignorant answer. They just told you that they don't want to deal with their own incompetence, so they make it your fault for owning aluminum wheels. Jeez.
hamburger
 
  1  
Reply Sat 27 Dec, 2008 11:46 am
a few points to add :

- we live in eastern ontario and the temperature changes have been fairly extreme and quick - from plus 10 C in the daytime to minus 20 C the next morning - repeated several times .

- the honda manual states rather vaguely : because tire pressure varies by temperature and other conditions , the low tire pressure indicator may come on unexpectedly .
meaning : we haven't quite figured out yet how this thing works .

- on my previous cars i always kept the tire pressure about 2 pounds above the recommended tire pressure - and i'll probably continue that practice .
i shouldn't have placed so much faith in the TPS .

- on my previous cars i always had my winter tires mounted on separate steel rims - so no tire change was necessary .
i was beginning to loathe to lift the heavy tires plus rims out of the trunk and stack them into the shelves in the shed - old age creeping up on me .
i wish the tire shops would store the extra set , but no one around here offers that service .

- disconnecting the TPS will throw the VSA (vehicle stability assist) out of whack - so that doesn't look like a good option .

- inflating with nitrogen did NOT fix the problem - higher air presssure did , at least for the time being .

again , thanks for yor replies . i'll be back once i have spoken with the honda guys (they'll probably quote from the manual - see above <GRIN>) .
hbg

0 Replies
 
Chumly
 
  1  
Reply Sat 27 Dec, 2008 01:00 pm
@curtis73,
In actual fact the relationship between pressure and volume can only be accurately described employing real gas theory.

As to nitrogen, it has has not been convincingly shown to have a real world practical advantage over conventional inflation of tires in conventional passenger car applications because:

a) the exterior of the tire is still exposed to sunlight / ultra violet / ozone / oxygen / salt / petroleum product contamination / other corrosive effects which far exceed any potential benefits nitrogen might have over conventional inflation.

b) the natural release of the tire's volatiles is going to dictate a maximum lifespan in any case, which again far exceeds any potential benefits nitrogen might have over conventional inflation.

c) all this is exclusive of road wear and flex wear, which are by far the most common true dictates of tire life, and which again far exceeds any potential benefits nitrogen might have over conventional inflation.

e) the smaller molecules of some of the gases as found via conventional inflation versus nitrogen is not going to have a meaningful effect on tire inflation stability, because most leakage is found at the tire stem and bead and not through the carcass of the tire itself.

PS: another potential cause of a rim leak is warped rims from hitting a curb or a beastly pothole etc.
0 Replies
 
Chumly
 
  1  
Reply Sat 27 Dec, 2008 01:09 pm
I should also point out that cast rims are not the only rim type prone to corrosion and thus leakage, steel rims can suffer the same fate. I should have also mentioned rims may crack due to the hitting a curb or a beastly pothole etc.
0 Replies
 
Chumly
 
  1  
Reply Sat 27 Dec, 2008 01:29 pm
Consumer Reports: "Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it's not a substitute for regular inflation checks." Results: only a 1.3 psi difference between air vs nitrogen filled tires after 12 months!

If you are concerned about the small amount of moisture in the air, find a place that uses an air dryer, but I say BS to that one too!

This nitrogen thing is a big scam!
0 Replies
 
hamburger
 
  1  
Reply Sat 27 Dec, 2008 02:05 pm
here is what TIRERACK has to say about overinflation of tires :

Quote:
An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when encountering potholes or debris in the road, as well as experience irregular tread wear. Higher inflated tires cannot isolate road irregularities as well causing the vehicle to ride harsher and transmit more noise into its interior. However, higher inflation pressures reduce rolling resistance slightly and typically provide a slight improvement in steering response and cornering stability. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures.


since the tires are overinflated by 4psi , it seems that i should be better off than with underinflated tires .
the next coldspell isn't expected for several days - MINUS 13 C for next thursday - we'll watch what happens .
for the time being i think i'll stick with the 4psi overinflation - the TPS seems to agree .
we have plenty of potholes - some are real monsters - that's the price we have to pay for living in eastern ontario . sometimes it's just impossible to completely avoid them , unless one wants a collision with another car .

all your comments and suggestions are certainly apreciated !
hbg

ps. perhaps i should consider a set of "solid" rubber tires for winter driving here - no air leakage to be concerned about .


Chumly
 
  1  
Reply Sat 27 Dec, 2008 05:09 pm
@hamburger,
I feel OK about tirerack.com, at least what I've seen of it. I bought four Yokohama iceGUARD IG20's for my Miata, it now justs rips through the snow and ice. I was going to buy them from tirerack.com but after shipping and exchange etc it was not worth it, alas.

Lowering the pressure down to about 20 PSI or so is an old trick to get better traction at slow speeds for snow and ice.
0 Replies
 
curtis73
 
  1  
Reply Sat 27 Dec, 2008 11:55 pm
I've always been a fan of Tire Rack, even before I had an Uncle working there Smile He was so impressed with the company that he started working there AFTER he retired from 27 years of racing.

About the time he started working there, I found a hookup with Toyo tires. I no longer buy tires from Tire Rack because of that, but my uncle has let me in on all their secrets. The bottom line is... they're really a top notch company. That's not a plug, its really a geniune endorsement. I find their prices and knowledge to be top notch, and if a 27-year racing veteran is compelled to work for them in retirement, that's a pretty good sign.

Ok... getting off the soap box now.
hamburger
 
  1  
Reply Sun 28 Dec, 2008 10:13 am
@curtis73,
curtis :

i think i'll keep paying attention to tireracks comments :

Quote:
This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures.


though i'm not planning to do any street racing - i'll stay at an extra 4 psi for now rather than 6 psi .
it's similar to the advice that "uncle tom" gave in mechanics illustrated some 40 years ago .
i am certainly not going to lower the tire pressure .
hbg
Chumly
 
  0  
Reply Sun 28 Dec, 2008 10:51 am
@hamburger,
Lowering pressure works, of that there is no argument, however you misunderstand my post, as it was within the context of the conditions I mentioned, it's not a long term nor high speed solution, it’s a temporary solution for snow and ice at low speeds, as opposed to not being able to have sufficient traction.

As to your belief that over-inflation of a modern passenger car tire has benefits that outweigh the disadvantages for modern conventional driving conditions, on modern conventional streets, with a modern conventional passenger car, you are welcome to believe that your advice is pertinent………but you are not likely to convince the modern tire manufactures nor the modern passenger car manufactures that they are recommending tires be under-inflated.

I'll side with the modern tire manufactures, the modern passenger car manufactures, the DOT and Transport Canada as I trust their testing methodologies and resources.
0 Replies
 
Chumly
 
  0  
Reply Sun 28 Dec, 2008 11:05 am
However I will say that +/- some few pounds is more a tempest in a teapot than a consequential change!

Those drivers that preoccupy themselves with such concerns in the context of modern passenger car tires, in conventional driving conditions, on modern conventional streets would be much better served to take their efforts and apply them to learning how to drive more effectively, as that is the single best way to improve safety.

We all have some Walter Mitty in us!
hamburger
 
  1  
Reply Sun 28 Dec, 2008 11:42 am
@Chumly,
chumley wrote :

Quote:
... conventional driving conditions, on modern conventional streets...


i doubt very much that many highways and streets in our city - and eastern ontario - can be desribed as "modern conventional streets" .
maintenance and upgrading has been neglected for many , many years .
the result : streets with potholes that just about swallow a car . every fall and spring city crews are scurrying about with truckloads of gravel and asphalt trying to patch up the worst roads - but the next frostheave or heavy trucks going through the city (old highway # 2 - the emergency/detour route for highway 401 - runs right through the city centre ) destroy whatever patching has been done .

repair shop owners have often appeared on newscast talking about the deplorable street conditions - even though they are benefitting from the extra business . drivers will often blame the repair shops for not having done a proper job when installing new shocks or tierods ... ... when they are sometimes thrown out of alignment after a winter's driving .

i suspect - as i stated earlier - that honda has not really done the best job when designing the TPS .
i wonder if other manufacturers have done a better job ?
hbg

 

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