I am about to aquire either a set of 17x8+35 and 17x9+35 BBS LM or 18x8+40 and 18x9+40 BBS LM.

Will either of these fit with these offsets? My car is not lowered, nor do I plan on lowering it.

Thanks,
Mark

 

rolled front and rear fenders for sure

 

Rolled fenders? That doesn't sound like something I would want to do. Does the 40 offset fit ok..? I would imagine the 40 is better then 35. Ideal would be +55 right?

 

Neither of the offsets are going to work without modification on your car. BBS makes a 18X8 ET 50 and 18X9.5 ET 55 for the car.

 

I wish I could afford new LM's, but 1k each is crazy. Are the +40 going to stick out by 10-15 mm? Is that what the offset means?

 

Pretty much, but it's a but more complicated than that as wheel/tire width plays a role as well.
Extracted from the fitment sticky at the top of the forum:

Based on successes and failures from many S2000 owners, we can use an offset calculator to figure out what other offsets and tires will work. These are minimum recommended offsets. You can use a higher offset if you want, and you will get additional fender clearance.

For the front:
205 tires: +43 offset minimum (6.5