i was looking to purchase 18 in tsw bremma but some of the wheel places ask me if my mercedes is base or sport package what are the differences between the base and sport package if any

 

Typically the major difference is the suspension components. Some models also have staggered wheel setups on their sport pkgs but not base models. Additionally, the wheel diameter is sometimes larger on sport models than on base models. They're just trying to make sure they get the right offset and plus 1 info so they sell you they right wheels. Look in your owner's manual and it'll tell you your factory wheel size (i.e. 7.5Jx17 front, 8.5Jx17 rear),and offset(i.e. ET32 front, ET 35 rear). Just keep in mind the larger you continue to go the wider you will have to go and at a certain point depending on the model you will have to account for a different offset to avoid rubbing.