i've spent alot of time looking at wheels but still need to learn and fully understand what the sizing etc means and what i can and cant fit

i have come to a decision on what wheels i would like to purchase for the new 2011 look of my car however no doubt theyl be impossible to fit,

can anyone help with out with what can and cant fit etc

i would rather pm my actual wheels im wanting as i dont wanna let it out the bag just yet but there image wheels

i have the choice of either 18" 19" or 20" currently have 18" with no trouble at all but would ideally like bigger if possible, also whats the maximum width i could have? the wheels i'm looking at range from 5.0j to 13.5j

any help is much appreciated thank you