my rationale for rpf1's in 17x8.
 

i've been researching wheels and tires as my next upgrade for the brz and while there are quite a few things out there that i think look great (te37's, 57xx, 57xtreme) i'm bound in by a few things:

1) most if not all of the suspension components except the eibach prokit that i have installed is most likely going to stay stock so nothing that can't clear existing suspension.
2) the ride is already just on the right side of being too harsh, so im definitely going to stay with a 17 inch wheel.
3) i'm not about being 'hellaflush' or anything but i would like to get rid of some of that stock sunken wheel depth while staying true to #1
4) i plan on getting something stickier but all season, pilot ps3s likely however i dont want something so wide as that i can't break it loose if i want to with stock power - so likely 245s and wider are out, though typically that width and wider breaks 1.
5) i'm not made of money like some of the folks on here seemingly are - anything more than about a grand for just the wheels is a total and complete non starter. also, this is already a second car so the wheels that are on there will be the ones that she wears 100% of the time.

based on these criteria i keep falling back to the rpf1's in the 17x8 size paired with a 225 width tire. i'm still debating whether the +35 or +45 offset looks/behaves better though im kinda leaning with the 35.

one thing that makes me think about the 45 offset though is that gold is an option and i think (strangely perhaps) that gold rims on a silver car (as mine is) looks pretty interesting but the 35 offset silver on silver is classic and would basically eliminate the wheel depth issue. however, i believe that either offset will work with stock suspension.

and i finally figured out why i really am not a fan of the black (or dark copper) rpf1's of almost any size - the rim is fairly thick and the spokes dont extend to the outside edge, so there is no contrast between the black tire and the black/very dark wheel which makes the wheel/tire combo look smaller and strangely out of proportion.

anyways, just throwing my thoughts out there - anyone that's running something that fits in these criteria that they're glad they bought please feel free to share!

I think these folks might be able to help you:

http://www.ft86club.com/forums/showthread.php?t=10257
http://www.ft86club.com/forums/showthread.php?t=37136

Similar criteria, but I went with OZ's.

anything particular about the ultraleggera vs their other designs?

I will comment on the aesthetics because the lack of concave on the 17x8+35 compared to the 17x9 makes a big visual difference. That was the decider for me, I initially bought the 8s and wasn't happy with the look of the wheel itself. In terms of offset it was fine, sits flush without poke but the face/spokes of the wheel bulges out. If you compare the 9" wide wheel it has a bit of lip to give it that concave and the spokes are more straight.

I'd suggest checking out images of each to compare aesthetics to make sure you know what it will look like as most images are of the nicer wider versions of the wheel. If the 9"+35 is too pokey you could run the +45 with smaller width tires and it should still clear (but check the rpf1 threads for confirmed fitments). If that doesn't bother you then i'd suggest +35 over +45 in the 8" width.

Functionally though, they're both fine, the 9" lets me run 245/40 tires at the track without making the steering feel too sloppy.

I liked that the spokes extend out to the tire, giving a bit of an illusion that the dia is larger than it is. I also like the thin spokes of the Ultraleggera, and OZ's reputation in the racing world.

What about a 17x7.5 wheel with a +40mm offset riding on 205/45-17 Max Performance level tires? Personally I feel it works the best for bringing out the dynamics of the chassis, plus with the better gearing and lower CG the car just does everything better. After I wear the stock tires down (almost done) I'm going back to 205/45-17 tires on my 17x7.5 +40mm wheels... precision and agility is just beyond that of any other wheel/tire size configuration I've tried, not to mention it has the best ride quality.

17x7.5 +40mm Enkei Fujin's with 205/45-17 Kumho Ecsta Sport LE's - the most agile and balanced setup that I've run so far on the car (because lowest unsprung weight and matching a good tire's tread width to wheel width is EVERYTHING for agility in handling and ride quality:)
https://vracer111.smugmug.com/Cars/S.../5315-3-X3.jpg

does the tire stretch of 205 and 17x7.5 affect handling at all?

im kinda partial to the leggera hlt's but they're starting to get into that 300+ per wheel action.

i just feel like 245's will bring a whole host of compromises with stock suspension, lots of folks say that +45 is a super tight fit and i dont love the stretched tire look - and the 9 inch wheel at +35 starts to look kinda ricey for my personal tastes though i do agree the aesthetics of the 9 inch wheel are great.

as you mention, most images are of x9 instead of x8, so its hard to get a great feel for how they would look on my particular car with its 1 inch drop but i think it might be the ticket.

205 tires are designed to fit on 7.5 wheels...not really a stretch. It's the perfect fitment for the size actually, a good 205 tire will have a 7.5" to 7.7" tread width which matches well with the 7.5" rim width. When you match the tread width to the rim width you are at the optimum match for handling agility. Yes, it does affect handling - it's noticeably better and more precise.

The main thing is the CG drop you get with the 205/45-17 tires really adds to the stability of the car while the smaller diameter and lower unsprung mass of the tires really add to acceleration, and precision steering and overall agility of the car - it responds quicker than before yet with more balance and stability. More grip too; because tire compound, not tire width, is what mostly determines grip levels.

Tire width will fine tune grip, but it also adds weight and looses some responsiveness - leading to an overall worse ride. If you are looking to make the car as light on it's feet and nimble as possible while still feeling planted and stable, you can't beat going to a 205/45-17 sized tire with a 7.5 width wheel. I also would not push the offset much past +40 if you are interested in agility... when you start getting to the +35 side of things you are trading responsiveness for stability with the wider track. As good as the 17x8 +36mm offset wheels I had used on track were, the car is just plain slower in responsiveness/precision with them and 215/45-17 Extreme performance tires (Kumho XS) than it is on 17x7.5 +40mm wheels with 205/45-17 Maximum performance tires.

It's all in what you want from the car, 17x8 wheels with 215/45-17 tires are excellent overall. In comparison though, 17x7.5 with 205/45-17 wheels will boost the reflexes, acceleration, and feeling of stability. At least that is my observation running them on the stock suspension. When you lower the unsprung mass...the car just rides much better and responds quicker.

Some potato quality pics on a silver for you, i don't have any decent shots of the 9" yet. Drop is 20mm with about -1.5 camber front and -1.8 rear so you'll have a tiny bit less wheel gap with 1"

This is 17x8+35
Attachment 121411

and this is 17x9+35
Attachment 121412

I like the look of the x9 wheel itself more but I like the way the x8 fits on the car holistically more. I do wish they had an ever so slightly darker grey color though in the size.

if you want an upgrade why not go with a 16"? cheaper too. cheaper tires too.