Hey guys. Need some helps on wheels and tires setup. I am still learning and would like to ask few questions.

Currently, I like to get Ruff Racing 278 wheels for my G. I am thinking to get 18” instead of 19”. I like the look 19” tires on the car. But I think 18” tires may give better ride. I called around and the spec I get is the following.

Ruff Racing 278 Wheels:
18 X 8.5 (F)
18 X 9.5 (R)
20mm for Brembo brakes (I have Brembo brakes on my 04 G35 Coupe 6MT)

Tires suggestion:
245-40-18 (F)
275-35-18 (R)

Is it a good setup?

I saw somewhere about 245-40-18 (F) and 255-45-18 (R) for the best stock tires setup. So, I was kinda surprised when I hear this Ruff Racing wheels needs 275-35-18 for the rears. Any input would be helpful. Thanks much!