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Discussion Starter #1
I've seen a number of threads and TSBs warning about using aftermarket (brass-lined) valve stem caps on TPMS Mazda3s, as galvanic corrosion can cause the caps to bond to the stems. I haven't been able to find a straight answer on if this is a problem with non-TPMS equipped Mazda3s, though. Are the TPMS stems made of a different metal than the normal stems, or is it just a more serious problems with TPMS since the stems are a lot more expensive?

I'd like to get a set of the locking caps below, but if it comes down to it I'm more worried about the caps binding up than neighborhood kids letting the air out of my tires.
http://www.spincaps.com/shoponline.html
 

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I had a set of aluminum caps, and those suckers corroded on there pretty good, despite removing them to check the air pressure every month or so. One day they were just stuck on for good. Oh, and I don't have TPMS.

If I was ever going to use a set of metal caps again, I would make sure to remove them regularly and keep the threads coated with some kind of water-displacer like WD40, no matter what they were made of.
 

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[quote author=dmention7 link=topic=69405.msg1204510#msg1204510 date=1171380921]
I had a set of aluminum caps, and those suckers corroded on there pretty good, despite removing them to check the air pressure every month or so. One day they were just stuck on for good. Oh, and I don't have TPMS.

If I was ever going to use a set of metal caps again, I would make sure to remove them regularly and keep the threads coated with some kind of water-displacer like WD40, no matter what they were made of.
[/quote]

Yep. Going through this right now. Funny thing is that it is on non OEM tires that I had mounted & not on TPMS either.

btw, how did you finally get your cap offs?
 

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I didn't, actually. Luckily the tires held a decent amount of pressure until I was ready to replace them. I would've been extra-pissed if they started to go flat with a lot of tread left, forcing me to either throw away good tires (well.... not that the RSA's were ever "good"), or pay a crapload to have the tires removed, valve stems replaced, and remounted.
 

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[quote author=dmention7 link=topic=69405.msg1261152#msg1261152 date=1173628234]
I didn't, actually. Luckily the tires held a decent amount of pressure until I was ready to replace them. I would've been extra-pissed if they started to go flat with a lot of tread left, forcing me to either throw away good tires (well.... not that the RSA's were ever "good"), or pay a crapload to have the tires removed, valve stems replaced, and remounted.
[/quote]

Yeah...the snow salt was the conductor that sped up this corrosion I guess. Now I have to decide if the tires can hold air or do I need the stems replace.

Tried to be bling & looked what happen! :?
 

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Discussion Starter #6
[quote author=NoVa link=topic=69405.msg1261142#msg1261142 date=1173627655]
Yep. Going through this right now. Funny thing is that it is on non OEM tires that I had mounted & not on TPMS either.
[/quote]

From what I can tell there are two problems:
1) Non-TPMS stems with aluminum caps. Non-TPMS stems may be brass, which reacts with the aluminum caps and bond.
2) TPMS stems with brass caps. TPMS stems are aluminum, so you're still got a galvanic bond.

The locking caps I was looking at should work fine on the non-TPMS stems, as brass on brass shouldn't be too bad. Aluminum caps may not even be a problem on the TPMS stems, although knowing how much the TPMS stems cost I wouldn't try it.
 
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