Two days ago I purchased a set of five-spoke 18x8 and 18x8.5 wheels from a 2007 350Z (picture attached). CL Member OneJay has them on his SC400, and I've been wanting them ever since on my SC300. I was told on the board that all 350Z wheels should fit on the SCs.

When I tried to mount the wheels today, they did not fit. The back of the wheel does not fully contact the hub. I pushed the wheel as far back as it would go and screwed in the lugnuts by hand (didn't tighten or torque them). As far as I know, I have no spacers and the SC300 brake system is stock. What gives? I was really excited to get these mounted. I read on intellexual that the SC300 has smaller disc brakes than the SC400, could this be the culprit?

Some 'Z wheels on SC' threads I have been reading: here and here.

Make sure the center of the hub is not rusted cus that will cause that not to fit, a little sandpaper or wire brush should do the trick. and make sure the hole for the hub in the wheel is clean also. hope that helps

How about some pictures of your hub? I know the bore size on the Z wheels are bigger than the diameter of the hub on the SC. The offsets are also lower on the Zs. The wheels should be fitting with no problem.

you should not have any issues with them at all . i run them on my car for drifting.

lemme buy them off you, ill get them to fit ... lol

clean the hub contacts on both the wheels and your hub with sandpaper

huhmm.... interesting... what do you think it is? hub? measure the hub's diameter or the circumference and match it up with the wheel's hub size and see if they match up.
Like it was posted above, maybe its rusted and you may need some cleaning?

I also have them and it fits, but i was recommended by BIG O tires to get different lug nuts. IT rubs like a **** with stock suspension and no pull of fenders. I didn't think it looked that great with my renaissance red so am trying to sell it.

Get a set of hubcentric hub rings.

Nissan hubs are usually larger than the ones of a Soarer/SC... 66mm (or thereabouts for the Nissan) vs. Toyota's 60.1mm. Likewise aftermarket wheels which usually have a centrebore of 73mm or so.

Are they required in order to mount the wheels?

And I'll try cleaning up the hub, it does look pretty rusty. Which grit should I get?

Hubcentric rings will not solve the issues. Hubcentric rings center the wheel properly on the wheel hub for balancing issues. As you mentioned the Nissan wheels have a larger hub diameter than the Lexus ones so they should slide right on. When you are just trying to mount them they should slide right on without any issues. However, i would suggest looking for some hubcentric rings later on just to keep the wheel balanced on the hub properly.

id say 80. if you have a rotary tool I would use that.

felixsc300, Information on hub centric rings, preventing damaged.

http://planetsoarer.com/offset/studs.htm

Thanks for the info everyone.

The previous owner installed aftermarket wheels on the SC, should there be any possible modifications I should pay attention to? I'm going to give it another try in a couple hours.

Not to mention taking the weight off the studs and putting them back where they belong, on the hub!

I would always use hub rings if the wheels aren't designed with a 60.1mm centrebore.