17x9 -VS- 18x9 Square
 

I'm debating between these two sizes for next spring.

17x9 +35 w/ 245/40r17 or 255/40r17
18x9 +35 w/ 245/40r18 or 255/35r18

Both have their pros and cons but which one should I go for and why?

18X9 looks\performance slight weight difference.
17X9 performance

I'd say 17s, generally it will weigh less overall, and will be cheaper! But if you don't care about performance much, 18s will probably look a little better.

The 18's will look nicer, but for me, I'd go with 17's because they weigh less and the thicker sidewalls mean that road imperfections won't be as rough on the ass bones. In the end, go with what your gut tells you, you are probably leaning more towards one or the other. Go with your stomach, it's hungry.

I compared Enkei RPF1's in 18X9.5 and 17X9 and the weight difference isn't too much, a couple pounds. The size of the wheel though on the other hand creates more rotational mass which might actually make the car work a bit more to get the wheels turning. Not sure how accurate that is, but it seems to be the case.

I'd go for 18", however tires should be 245/35/18 if you want it as near as possible to stock diameter

Well, I'm all about doing things classy but functional. I'm sort of leaning towards the 17's as they'll be lighter and cheaper to run for the long term. They just don't grab your attention as the 18's do. The 18's look quite a bit nicer but at the expense of weight and the cost of tires can be signifcantly more.

My car is a daily driver that may see a small amount of lapping days per year.

This

I picked 18's because 17's don't look big enough in my eyes for the car.

I'm a meaty tire kinda guy.

It'll help a lot if you list what you plan to do with the car, and also what you feel the pros and cons are for you.

If you want pure performance for a time attack type situation, you're better off with 8" wide rims with 225's.

I'm not a fan of buying twice. An 8" width rim with 225's?! Might as well just keep the stockers lol. Sorry but that's not what I'm looking for. Even if I was time attacking with the stock car, I would just stick with the stock wheels and wrap them with sticky 225's

The car will be a DD with little track time. Eventually, it will be turned turboed so may as well go for the wheel size that'll accomidate that. Plus, 9" width on all four corners looks business. I'd rather have too much grip than not enough.

I guess I can say that the cost of tires is pretty important to me when talking long term. A 17x9 with a 245 would probably be most economical in terms of performance per dollar. But 18"s look more satisfying. That's the delimma I'm having. Aesthetics versus running costs. I may not be satisfied with the look of a 17x9; whereas, 255/35r18's can rack up a tire tab quite quickly.

I may have to flip a coin with this one. The votes so far are pretty even too lol.

^^ Wider != more grip... sticky tires need heat to generate full grip, and going too wide can actually give you less grip because they won't get warm enough. My 17x8's with 225's weigh less than stock, and are WAY stickier, plus a 225 will perform better on an 8" rim than a 7" rim.

IMO, forgetting budget, you should go for the 18's since you seem to be looking more for how they look than ultimate performance on a track.

If you want to consider the long term budget, your best bet is to get a set of 17x9's for track tires and then whatever you think looks good for the street with average summer tires. Sticky tires won't last that long at all (I'll be lucky to get two summers out of my ZII's at about $1k per set), so factor that into long term costs as well.

And if you choose a high tread life tire over 300 rating like a MPSS you'll be smarter money up front to just something else to consider either way you go.

Yea, I'm looking more along the lines of a Yokohama S.drive , Falken 452 or something in that range. People must got deep pockets to DD on Dunlop star specs or other extreme summer performance variants that wear fast.

At my current stock power level, it's too much tire to run 255's that are sticky summers. A mid performance summer 255 would be great for a 17x9 or 18x9 I believe. For what I use my car for, it should be optimal.

I do plan to wrap the stock wheels with Hankook RS3's. It makes the most sense to me to just use the stock wheels with sticky summer tires when only at the stock power levels or basic bolt-ons.

It's so hard to decide... 17"s or 18"!!!!!

Have you actually priced out wheel and tire costs for what you're looking for? That should really guide your decision more than people on a forum telling you what to do.

As for your stock wheels, IMO you should sell them and buy a set of light 17x8's for the RS3's. Dropping ~5lbs per wheel is nothing to laugh at, and a set of used RPF1's shouldn't be more than ~$600-700.

your exactly right 18s will look better but the 17s may perform better

That's like the weakest recommendation of wheel aesthetics ever LOL. Convexed RPF1's are ugly as sin. No, I will never waste my money on a 17x8 wheel when the stock is fine. If anything, I'm already thinking about 215/45r17 R-comps wrapped on the stock wheels. That should be PLENTY of tire for the car. Light weight wheels are best, of course. But I'd rather spend my money on something significantly wider. 9" or go home... It's for later when this car has some REAL power. An 8" wide wheel at that point just won't cut it. You're pretty much stuck to a 235.

I absolutely love the fat bulge look with a 255/40r17 on a 17x9 rim. That's what I run on the back of my mr2. Aesthetics and raw functional is my taste. I will admit that I'm heavily leaning towards going 17x9's with the FRS. Functional fat tires will look incredible on all four corners.
http://i94.photobucket.com/albums/l1...2/DSC05553.jpg

https://scontent-b.xx.fbcdn.net/hpho...85725941_n.jpg

18x9.5 with 265/35 tires

because #bootymeat

This post makes it pretty clear that you're after look more than function all around.

Go spend some time in the HDPE/Track section and see what people have to say about tire/wheel sizes and lap times. CSG runs 17x8 with 225's on their shop car because that was faster (with actual quantitative testing) than 17x9's with 245's.

If you think saving more than 5lbs per wheel isn't significant on a track you might want to rethink spending any money on R comps too. Have you considered what supporting suspension mods you need to take advantage of the grip from R comps? They'll need much higher spring rates than most people will run.

I'm not saying you shouldn't go wider if you like the look, but wider will not always give you more grip or make you faster.

FWIW, if you wanted a bulged look you can put a 245 on an 8" rim safely, it just won't be quite as quick as if it were on a 9" rim (we're talking a couple tenths per lap, not huge). A 245 on a 9" rim is going to be pretty square, almost bordering on a slight stretch.