looking @ Rota's website now, they have RBs in 15 x 7.0, +25/+30/+35/+40, tires i'm planning to use are 195/55R15 Advan Neova (there are no wider nor lower tires available), i'm currently lowered on Eibach pro-kit springs

will i be rubbing? i want the lowest offset i can get to get more lip i've already shaved off a part of the inner flares for my 205/50R16 Neovas before to not rub

 

Those tires are smaller than stock tire diameter which is good.

Run with more negative camber if you need more clearance.

For your lowered MINI the +30 and +35mm offsets are probably the better sizes. I think that both can work but +30 does stick out quite a bit if that is OK with you. About +33 tends to be flush with the top of the fender trim and then negative rear camber brings the top of the tread back in tucked under.

Always run tires that are smaller than stock if you do get these rims, shoot for under 24" if you can.