Alrighty, here goes. After many mumblings about German GS owners fitting RS/RT 17" front/rear wheels in place of spoked 19/17" front/rears and after much Google-fu along with plenty more alt-tab between Google translate and some German GS forums...I ordered a set of front wheel adapters from Rennkuh.de. Again with the help of Google translate, I contacted Michael Walsh from Rennkuh Shop and arranged shipping to the U.S. as their website allows orders, but not shipping to, North America. The adapters are about 100 Euro, plus 40 Euro air freight to my house. I tracked down a near new set of R1200RS takeoffs for a song. The whole package (wheels/tires/TPMS/rotors/et al) cost me a little over $1K shipped to me with nearly new Pilot Sport 4's. Now for the fun parts. The offset combined with extra width of the 5.5" RS rear wheel causes the outside edge of the tire to hit the stock GS muffler. The offset is also visibly incorrect. Rennkuh offers pre-machined rear wheels for this swap, but I decided to gamble with the deal I found. After a little measuring, 5mm machined off the bolt surface of the RS wheels seemed to do the trick. My Rallye does not have a centerstand, so I don't know if that measurement works for bikes equipped with one. I also cannot confirm how much Rennkuh machines. The possum catcher still fits. Factory rear lug bolts work, although a shorter length wouldn't hurt as the length of the OEM bolts comes close to the ribs on the inner final drive housing. As for the front, this is where the Rennkuh adapters come into play. The kit includes two sets of spacers for the front calipers to fit either 320mm or 350mm rotors (best I can interpret from the writing on the packaging). For the RS front wheel, I used the larger of the two sets of spacers. There are also some smaller bushings that allow the calipers to align on the fork mount. The first image below is probably confusing, but shows the parts. Next time I remove the calipers, I will get a couple detail photos. The adapter kit also includes two bushings that insert into the front wheel bearings that provide proper spacing to fit GS front forks. The stock GS axle is used. One bushing has a recess that allows the axle to sit inside and align it perfectly. Next time I remove the axle, I'll get some details of those bushings. Lastly, the stock front GS fender meant for 19's looks horrendous with a 17" wheel. I'd seen a picture of a GS with 17's that used an S1000R front fender. The RS fender looks very similar. Unfortunately, they mount differently. So...brackets were fabricated from 1"x1/4" aluminum flat bar. A couple holes...a couple bends...some countersinking on the lower bolt thru holes, and some tapping on the upper holes where the S1000R fender mount, et voila! Front Fender. The RS front ABS ring lines up perfectly with the GS sensor. No problems there. I do need to research further how to get the TPMS sensors to talk with my bike though (dealer? GS911? special tool to activate TPMS sensors?) After a quick spin around the block and the results are interesting. The front end is very responsive and it almost falls into turns. Time will tell if the handling and ride are worth the cost, but I enjoy the prospect of saving my TKC80's for the dirty stuff instead of burning them up on canyon runs, commuting or long highway burns. As for questions or comments, let'er rip and I'll do my best to answer or provide insight!