Existing on standard 17" lexus wheel, tires as follow spec:
Front : 225/45/17
Rear: 245/45/17

Now, I'm waiting my new wheel from Japan Weds Maverick 19" F 8" and R 8.5" with Spring KW.
Just no idea, what's tires spec should match to make my car look gorgeous and achieve most possible riding comfort. My Idea plan to have like this:

Front: 225/40/19
Rear: 245/40/19

Some advise that, all four same size and spec for able to rotation - 235/35/19. Please advise.

 

First of all its ADVICE NOT ADVISE LOL.

Second of all, I'm guessing you have a RWD IS250 from the specs of your factory wheels. 225/40 & 245/40 is a good tire size for your new wheels cause you're still running the same width.

As for the idiot that advised you to get 235/35/19 all around, don't even listen to him. You're running staggard now why in the world would you run non-staggard!??! You're not AWD, so cross that out and run the size you mentioned, which is the 225 & 245/40s

Hope that helps. BTW, DON'T ever rotate your wheels!!!!