You could make a set yourself by using a couple sets of old 10" wide spoke rims. That is what I was planning on doing if I decide to go pro stock. I've even got an extra set out in the shop for it just in case????? Those 10" wide rims are a dime a dozen. Maybe put an ad in the thrifty-nickel for a couple of weeks.
Adrian, Try US Wheel (Summit sells them). I got a pair of 15 x 10 - 8 lug with custom backspacing and they were $ 60.00 each. 12 or 14" wide will be a little more but I don't think they will be too much. Unless of course you wany aluminum one piece forged with all the bells & whistles. LOL
Adrian, check out marsh racing wheels! they have steel wheels, and if i remember correct an 8 lug , 16 " x 14" was $139.99 and 16" x 16" they make you call a get a quote i think they were $159.99. They also say they will make the rims with the backspaceing you want for no extra charge! Checkem out!! Dont know the exact web address,try www.mrw.com!!!! or just google marsh racing wheels!!!!!!!