Thanks guys, for all the information.
I was planning on using the Firestone Deluxe Champion tires; they are specifying a 2.15 rim. However, according to the pdf from 4g, I can go 2.5 on the rim.
2Many, thanks for the links. Exactly what I was looking for. I'll sit down tonight and read through them in depth.
pago, good info on Buchanan's, I may just put it in their hands, but I'd really like to build that wheel if I can.
""I will guess that cost IS an object here. My best advice is that you need to adjust your thoughts a bit. The XS is a 60s 70's design street bike. The 2.15 rear rims were considered state of the art for 70's street design on Japanese and Euro bikes. If you go wide you need to bring a lot of things along for the ride. Even going to wide rims leaves you with a fairly narrow hub design with 90 degree bent spoke heads so only so much wheel stability is available. Note the dirt bike hub above has a much wider base and uses only a slight bend of the spoke head theoretically creating a more stable wheel overall. ""
4G, you posted that in the second of the threads that 2Many linked to (sorry, I'm not sure how to pull a quote from another thread and have it show up here.) I'm curious as to how wheel stability is affected by rim width. It seems like the wider the rim and hub, the stronger the wheel? So adjusting rim width without taking into account hub width could lead to a less robust wheel?
One other thing - I've read that the Firestones are crap tires. (I know my dad hates them, ever since a set failed on his '56 Tbird convertible. That was probably 50 years ago, but he still holds a grudge.)
Any suggestions for new tires? I like the traditional look of the tread on the Firestones, but that's of secondary importance if they are likely to fail.