Does anyone know if there are any swing arm extentions made for the GS??  Nothing too extreme.  And will the rear wheel off of a newer model GSXR fit??  I would like to run something bigger than the stock size tire.  Especially if I can do the extention.  Thanks in advance.

buy an extra swingarm and have a stretch fabricated

biggest rim that will easily swap is a 4.5 x 17   99-up kat600-750 /89-90 GSXR 750 / RF600

if you get the swingarm modded to fit a bigger rim.... then you can go with a 6.0 x 17

if you need a complete 5.5 x 17 rim with cush/sprocket/axle/rotor/caliper/caliper bracket.... I got on in NC  (92GSXR1100)