I'm running 275/40 ZR 18's on MY car with the low profile tires there is a larg gap between the tire and the top of the wheel well.How much can I lower the car and who makes the kit?

 

There are lots of lowering kits out there that will lower anywhere from 0.75" to 2+ inches. You need to decide how low you want to go, however I personally wouldn't recommend more than 1.5" since you will essentially be eliminating all suspension travel if you go much lower. Also make sure to replace your shocks with appropriate ones (revalved Bilsteins, Konis, Penskes if you have too much money ) when you are lowering since damping requirements will be different for a lowered car. Good luck.