Back to somebody's original comment, you need to keep the diameter (tallness, in effect) the same or very close to original OEM specs - just about 25" up front and 26" in the rear. The original rims where 18" and 19", but you are changing to 20" front and back. So, you need to select a 20" tire that maintains the 25" and 26" relationship.

OK?

You picked a 275/30R20 for the rear. That's fine; it's about 26.5" tall, close to 26".

You picked a 225/35R20 for the front. It's 26.2" tall, which is too much taller than 25". Remember?

So try a 225/30R20 up front. It's about 25.4" tall which is a lot closer to the 25" you're trying to maintain.

Putting 20" wheels both front and rear is unusual, but it seems that this tire size works: 225/30R20 (25.4") front and 275/30R20 (26.2") rear.

I know it's all pretty confusing, but your car should look swell with 20"s all around.

PS: Are you sure that all of the rims you are buying are 20"s? The Bazo link you just listed says 19" and 20", which makes more sense. All of this stuff is pretty expensive, so double/triple check everything before you order it. Don't take my word for this - try to get familiar with that tire/rim calculator yourself until you are comfortable with all of this mumbo jumbo. It costs too much money to make a mistake.

Good luck, mate.