I just picked up a set of 18x8's and need to get new tires. The wheels have a 35mm offset so I am limited with my tire decisions. Here are my choices:
225 - skinny tire but fits perfectly
235 - height is smaller than stock and makes the wheels look small
245 - with 35mm offset, causes rubbing in the rear with passengers in the back

Different tires have different contact patches. The one tire I decided to go with (Nitto 555) has one of the largest contact patches. Therefore if I put on 225/45/18's the wheel will fit perfectly and fill out the wheel well but it will also not look as skinny.

 

I have 235/40/18 on my 18x8's and they fit perfectly with +38 offset. If anything, that extra 3mm will help you clear the suspension more, though I don't know what generation Max you have. As for wheel gap, lower your car. If you are gonna drop $1000+ on wheels and tires, might as well spend $150 on some springs.

 

2K2 6spd with Maxspeeds lowering springs.

The reason I ask is because I have two sets of wheels sitting here at the house. One set are Mille Miglias 18x8 with Kumho 235/40/18's and the others are G35C wheels with 225/45/18 front and 245/45/18 rear.

The G35C wheels are Michelin Pilot Sports with 50 miles on them. Others 5th gens with these wheels have rubbing issues in the rear when there are passengers riding in the back.

When I had the Milles on, the 235/40/18 looked very small. It opened up a gap all around the wheel that did not look good.

Ideally I would like to have 245/40/18's but I think they will rub.