I got my SWing used at 17,000 miles and now it has nearly 21000 miles and needs a new set of tires (rear mostly but will replace front at same time). When I first got my SWing I noticed a 'hissing' sound when I would fill up the front tire - so I took it to the dealer to have them check it out. The tire was fine but the front valve stem rubber was horizontally 'cracked' and needed to be replaced (and it actually broke in half in the mechanics hand as he was removing it - so they say). I try now not to stress/bend the front stem when I put in air; however, I am looking at alternative metal valve stems that may better resist forces acting upon it so as avoid a repeat of what may have happened to my front valve stem. I got on a couple of bike forums and found that some riders have elected to go with metal valve stems (that seal on outside and inside using rubber gaskets). There are online sites that sell metal valve stems and the price differential seems minimal between metal vs. OEM valve stems. The OEM front stems (7/8 inch high off rim) bend a lot so I am assuming that there is no metal that extends fully down the stem into the tire. I am torn between using using 3/4 inch metal stem that goes straight up vs 85 degree metal stem that does out the side -but my gut says go with the 85 degree as it will likely be easier to add air. The back wheel OEM is metal with rubber where it joins the wheel - and it seems as if the metal must extend directly into the tire - but this is just a guess. For the back I am thinking of staying with OEM or going with the 85 degree metal stem that is oriented 180 degrees (i.e., does not go through any support bracket). I am GUESSING that these metal stems will fit my SWing if it has an 11.5 mm hole (0.453 inch) in the rim ; however, the rear 85 degree metal stem may need to be oriented 180 degrees from the existing one as it likely will not line up with the bracket that helps position/brace the OEM rear valve stem from excessive flexing.
Finally, my questions (assume that either OEM or Metal get changed out every time a tire is changed):
1. Can anyone confirm that the wheel rim hole is approximately 0.453 inches in diameter?
2. Have you had any bad stem experiences that would lead you to consider installing metal stems?
3. Do you think that it would be a good idea to (at tire change) install metal stems on the front and if so, would you go with the one that is straight up or the 85 degree model?
4. Do you think that it would be a good idea to (at tire change) install metal stems on the back?
5. Is there metal throughout the OEM front stem? Rear stem? How are they constructed?
6. Any other comments/suggestions regarding stems?

Thanks for considering this topic.

REFERENCES:
Motorcycle Forum Discussion on Stems
http://www.goldwingfacts.com/forums/view_topic.php?id=128305&forum_id=1&jump_to=1507096

http://www.st-riders.net/index.php?topic=3887.0

http://www.goldwingfacts.com/forums/forum1/116050.html

Links to Metal Stem Supplier Sites

1st one listed for front wheel and 3nd to last listed for back or front wheel
http://kurveygirl.com/shop/index.php?cPath=27

http://yourtireshopsupply.com/category/9_419/passenger-valves-enkei-valves
The manufactures noted for metal valves seem to be Enkei, Haltec, and Beico.
Manufacturer Sites
beico.com
haltec.com
enkei.com and blog.enkei.com [can't actually find Enkai wheel valve stems]

Thanks Bill for your comprehensive response. I just put a pair of Arietes valves ($30 for a pair) on order - one for the front and one for the back wheel (went with KurveyGirl.com as they are an adjacent state). Hopefully they will be installed next week. Do you know if they use a standard Honda equivalent stem internal core that can be removed by standard Honda equivalent stem core extractor tools? The Arietes looked squatter, more robust, and with a simpler nut-washer sealing mechanism than other manufacturers noted in my post - all of which I think is a good thing.