Can you put different size rim on G35X? Or
Does all the rim have to be same equal size because it AWD? If yes, WHY?

 

They have to be the same diameter and width all around. I think the tire sizes even have to be the same to. If they are not, i think over a period of time it will damage the AWD system. Someone w/ more knowledge on this could explain it much better.

 

Thanks for your input.
The reason i asked, is because my cousin has really nice rims from his G35 coupe(his GF told him to sell it because it's inconvenient)


I also consider about the ride confort for the rims.
What's best size for the rims and tire without loosing the confort?

 

Stick with the same size on all 4 corners.
If by "ride and comfort" you mean smooth, then you probably want to stick with the 17's on an X.

Usually:
bigger rims = less rubber (sidewalls) = better perf. = feel more bumps in road.
...and of course the type and quality of tire is a huge factor in all of this.

 

sorry if this is a bit of off topic, but if the rims where change from the 18" to a 19" on X. Would it cause any problem and can the OEM break handle it?

 

I have a set of 19x8.5's on my X with 245-40-19 rubber... I felt hardly any loss of comfort.
The change in handling however is absolutely amazing.

I swap back to 17" Blizzaks for winter driving and I again feel no comfort change.