In terms of spelling, wiener is a variant on the spelling of weiner, but both are recognized as correct by Merriam-Webster dictionary. The reason for the two different spellings is that in English the "ei" is pronounces an "e" sound, but in German it is the diphthong "ie" that represents the "e" sound. Thus the spelling wiener is the proper spelling taken from the German language, but the spelling weiner makes more phonetic sense in English.
Wow, your wiener is huge. I don't think I could ever fit that whole thing in my mouth.