niche wheels

Hello All, My factory tires have to be replaced. And I decided to replace rims and tires at one time. I need an advice for the tires sizes. I plan to install "20 Inch Niche wheels m191 gamma bronze" Front: 20x9, ET 38 Rear: 20x10.5 ET 40 -- The original: 245/40ZR19 8.5Jx19 ET40 275/35ZR19...