I did a quick search here and elsewhere and think it’s a disulfide of some kind but not positive. Any confirmation or other ideas?
Oregon Chardonnay (2014) has a rubber aroma when first opened and a slight bitterness on the finish. Decanted the wine and periodically retasted over an hour+. Both the rubber aroma and the bitterness got progressively worse over time. Dumped when the bitterness went past the unpleasant threshold to the gag stage. Color was fine initially and stable.
Sulfur compound(s) in a wine made in a reductive style.
Next time, try putting a pre-1982 penny in your glass.
Eric is correct, although the fact that it got worse with time probably means that it’s beyond saving with copper.
If by reductive, you mean H2S then I don’t think so. I have plenty of experience with H2S and while I will never rule out any possibility, this was vastly different than any prior experience I’ve had. The aroma was different and I honestly don’t recall the bitterness on the finish of any of the H2S flawed wines I’ve had in the past. This is why I think it’s past that into one of the disulfide compounds.
What begins as reduction can end up as mercaptans. That’s why I made the comment that it is probably beyond saving.
Just throw a penny in next time. If it’s not disulfides, it can make a big difference. (Can be a modern penny–all you need is some copper surface area-it doesn’t have to be solid copper. I have couple of pennies that I drilled a small hole in and put on fishing line to make them easy to pull out of the glass)
The rubber tire aroma is probably a mercaptan (also called thiol), which is the analog of an alcohol with a sulfur atom replacing the oxygen. There are all kinds of mercaptans, some of which smell pretty bad, and some of which offer more interesting aromas (the smell of coffee, for example, is in part due to a mercaptan based on the compound furan: Furan-2-ylmethanethiol - Wikipedia). But I have yet to find a source that definitively identifies the dominant smell of new rubber tire.
Alban Syrahs of old were notorious for this rubber tire smell. No amount of aeration would cure it.
This is one of the best summaries of compounds responsible for the variety of wine aromas I’ve found:
Read through the comments to this little essay to see what chemists do for fun 
https://blogs.sciencemag.org/pipeline/archives/2012/07/26/amines_and_the_landscape_of_chemical_stink
Since we’re talking about sulfur compounds, here’s a fun article to remember next time you eat asparagus (which I always pronounce as "ah-sper-ah’-goose, in honor of a Swiss colleague and friend who said it that way):
And another detailing the sulfur compounds responsible for the nasty aromas in skunk spray:
And in my googling, turned up this, um, interesting link, which I wasn’t able/willing to follow to the end:
Some sulfur compounds are tenacious such as those responsible for “bad breath”. They can be broken down through specific reactions but are normally very stable. Could be responsible for the wine flaw.
An interesting note on some coffee sulfurs. Some are so oxidative that they oxidize faster than antioxidants which made them fantastic at helping to preserve foods and beverages. The only problem is they reek of coffee and therefore are basically useless 
Tom
I think most wine geeks should have both a copper cup and a silver cup around to pour their fetid, high end, failed swill into for parlour tricks.