17x8.5 or 17x8 both ET40
 

Which size should I go with? I'm concerned about rubbing and also wonder how much tires cost for each or if it's the same.

Sizes:
 

I'm running 17x7.5 in front & 17x8.5 in the rear. Running 225/45-17 in front and 245/40-17 in the rears. NO Rubbing at all. The wheels are 98 M3 DS2's and the offset is 40. So the rubbing issue isn't a problem with that offset and tires.

My Kuhmo Estca SPT tires run about $100 each. Check out tire rack for pricing.

Thank you! I'll check that out. You think I should go smaller in the front like that? Or just throw 8.5 on all of em?

I have run 17x8.5 et41 all the way around and had no rubbing issues with 245/40-17 tires. Used them on bils with H&R sports and now with TCK SAs.

So you ran them with a drop with no problem? Also do you think 235/40-17 or 245/40-17 would look better? Sorry about all the questions I wanna make sure my 1000+ dollars is spent correctly! :)

Tires
 

Yes, with a drop, have to crab over speed bumps to avoid scraping underneath.

I have Bilstein Sport shocks and H&R sport springs all around.

I think that 255/40-17 would look even better, but 225/45-17 front and 245/40-17 rears keeps the tire diameter the same front to back.

including a picture of the car.

Thanks I think I've almost made a decision! XD It's between 17x8.5 all round with either 235's or 245's or 17x8 front and 17x8.5 rear with matching tire widths.

Yeah, when you get to this size you need to make sure the wheel to strut clearance is adequate. This is much more of an issue with coilovers than with strut/spring combo. With coilovers you want to make sure the spring will sit high enough that the wheel doesn't interfere. If it does you can also just run a small spacer to push it out.

My wheels currently clear the springs by about 5mm. The rear has a good bit of room, it's the front that may pose a problem. 255 might be pushing it depending on whether the particular tire tends to run wide or narrow. I should mention that the 245/40s I am running are Hankook Ventus V12s and they tend to run narrow, so that helps clearance.

Thanks for the help guys! I think I got it from here. =] I'll just do some typical googling now!

So I think I'll do 8.5's all around! with 235/40-17 ^__^ What is your opinion? You think it will fit the wheel well nicely? Also if my ti is bone stock with no drop you think the 8.5's will have rubbing up front?

Edit: I will be dropping it in the future.

A staggered wheel setup will not only introduce potential oversteer, it will also require you to dismount, remount and rebalance tires every time you want to rotate them. Since most low profile tires are directional, they can only be rotated from front-to-rear/rear-to-front and must remain on the same side of the vehicle. With a staggered setup, you can't even do that.

What do you think about what I just posted?

I ran 235/40 Toyo RA1 R-comps on my 17x8 OZ Superleggeras. R-comp tires typically run wider than regular street tires, so a 235 would be more like a 245. On a 17x8.5, 235's might look slightly stretched.

That's cool! I like the slightly stretched look. Do you think I will have any rubbing issues? Btw, thank you for all of the support and everything I absolutely love this website! I will be hanging out on here more often haha. :)

Nah, they shouldn't rub. As Spidertri said though, I'd be more concerned about rubbing on the inside. For reference, my superleggeras were 17x8 et40:
http://www.318ti.org/forum/showthread.php?t=24365

Yeah that's what I'm worried about is the rubbing on the inside =\

I ran 245 Michelin PS II's on an 8.5" wheel and even those looked slightly stretched. It wasn't bad, but the sidewall definitely wasn't flush with the wheel lip.

So I can run 8.5's with no problems?

You think I should just go with 8's and call it a day? haha

No go 8.5

Alrighty then! haha so it will go up front with no rubbing?

Please read post #4

Okay okay. XD! I'm sorry haha. I just wanna make sure this is my first mod on my car so I wanna get it right! XD

Lol. It's straight. I remember my first mod. Hahaha

Well since we're still here. You think I should do 235's or 245's? Just look wise since I know both will work. haha.

Not sure what suspension you are running but with stock/bilsteins/konis you *should* be fine with 8.5s in the front. When you move to coilovers it gets a bit trickier. FWIW, there are many autox/track guys running 9s in the front with little modification.

When looking at tires one rule of thumb I have heard is to look at the published "tread width" and see how that matches up to your wheel width. You'll get better performance if the tire is slightly stretched on the wheel.

Well then 235's it is! Thank you guys! I'm ordering tonight! I can't wait until these bad boys come in! I'll get some pics up! ^__^

Not to make this more difficult but there is no sense in going to an 8.5 for 235's. BMW ran 235/40/17 on 17x7.5 on all the 95 M3's. By going an inch wider on the wheel you are doing nothing but adding weight (in one of the worst places) for no reason.

Well it seems I did not order tonight haha. My mechanic wants me to come by the shop tomorrow. He says he can probably get me a better deal for the amount I am going to spend. So I might be getting some rims tires and lowering springs. =] I'll let you guys know and post pics as soon as it's all together!

BimmerBum is right- if you are going to run 235's, it is not necessary to have an 8.5" wheel width. I'm currently running 235's on DS I's (7.5" width) on my ti and the fit is perfect. The extra rotational mass that an 8.5" wheel will have is detrimental and by slightly stretching the tire, you're making the wheel more susceptible to curb rash.

Yeah, I didn't mean to imply running 235s. I meant look at the tread width and see how it matches up to your wheel width. For example, the 245 hankook ventus v12 has a treadwidth of 8.4" so it matches up nicely with a 8.5" wheel. The 245 hankook RS3 has a treadwidth of 9.1" so while it can be run on an 8.5 you might see and feel better performance on a 9" wheel. But if you are running a 9 why not go to 255?

Well the 235's I was going to get also had a 8.4'' tread width, but I'm visiting my mechanic today and hell sort me out haha.