i want to fit rota rbr wheels for my z 17*9.5 -19 rear and 17*8.5 +4 front.

i want to lower the car 1 to 1.25 inch

also install zg flares

help me find the correct suspensions and springs ,

is it important to convert the springs to coil over ?

what to buy to convert to coil over?

Whoa, lots of questions there. First start off with what car you have and what does it currently have on it.

Second. Do some research on this site. There are many cars with larger tires that you desire. Also, and probably the best recommendation, try Hybridz.org. They are more into heavily modified Z's. Most folks here like to keep them in as new or as new +1 condition. Good Luck.