I see 18x9.5/18x10.5 is a popular option. I'm not sure I need the weight with only stock power going to the ground. RPF1s in 18x9+35 and 18x9.5+15 seem like the lightest options at a reasonable price. Paired with 245/40s and 265/40s should give me a good bit more grip with about 5lbs of savings per corner. Am I missing anything? Are there other options?

 

If you want more grip, there are always softer and grippier tires. In SCCA racing, I am limited (by rule) to a 245-40-18 BFGoodrich R1-S and those tires will out-corner just about anything this side of a Hoosier R7. But that's an extreme example and not one for the street. You're on the right track with the Enkei RPF-1 and tire sizes, although I like a 275-40-18 for the rear, as there's more choices in that size.

 

I've learned and have come to love my RPF1s. My 18x10.5" are 19lbs each. A very close 2nd would be 1st generation OEM 'track' wheels. I've seen them 2nd-hand for the $400 to $800 range when you can find them. I believe they are similar weight but they are forged where the RPF1s are cast aluminum.

 

Just a slight clarification: the RPF-1 use Enkei's MAT technology, which the company claims produces a wheel stronger than a simple cast wheel. I use these wheels for racing as they are the lightest and cheapest option available. For the street, my Z uses BBS RG-R forged wheels and they are quite a bit stronger, only a few pounds heavier, but way more expensive (but affordable if you find them on the classifieds section of this board).

 

You have to account for the heavier tire also