okay, got the stock tire up there.. the tires only have about 5k miles on them, maybe even less so thats as big as its gonna get (245/60/18) the tire fit no problem, also have a 5 gal gas container up there with it, fit was kind of snug, you could definately fit 2, maybe 3 up there with the tire, if your tire diameter is any bigger you might have to be careful about the size of the gas cans you use, depending how you mount it you could even probably use your spare tire to hold more gas cans (if you have your rim facing downwards and your mount doesnt stick up too far)
i did notice that i had to maneuver the tire around the bolts for the basket mounts, my crossbars are smaller than the stock ones though so yours probably wont stick up as far.. either way im runnin back out there now to chop the ends of the mounting bolts off since they stick up unnecessarily far... see what the VX has done to me.. it was a perfectly good basket, bolted right up with no problems.. and i had to go and modify it anyway! (debadged fairing, covered the fairing in carbon fiber, built light rack for basket, now trimming mounting bolts)

see my gallery for the full sized pics