[SLOWER]

Originally Posted by MickAv8r

Would love to see some more pics, especially detailing fitment. I'm looking at grabbing some EC7s for track duty and trying to decide between 8.5 ET35 and 9.0 ET42 - I know the 8,5 will fit, but the 9s are currently cheaper.

Did you end up with these?

[etinifni]

I've been thinking of going with the deeper concave ARC-8 version with 235/40/18 tires but in that thread people were going with 255's. What are the pros/cons of these size choices?

[alohasurftoad]

Originally Posted by etinifni

I've been thinking of going with the deeper concave ARC-8 version with 235/40/18 tires but in that thread people were going with 255's. What are the pros/cons of these size choices?

the factory F-series wheels/tires have a 26"-ish diameter. 235/40/18 will create a larger wheel gap and cause your speedometer to read higher than actual and odometer to accrue more mileage than actual by a small percent. 235/45/18 would be a better choice. although it is of greater diameter than oem spec it will fill the stock wheel gap a little better and cause the speedo to read right on (bmw speedos tend to read 4% higher than actual)

anytime you change from factory spec it will change the performance. typically, larger changes are more noticeable.

diameter affects final gearing which affects speedometer and odometer. overall height and wheel gap also change.

obviously there will be more grip as go wider but it increases friction drag. tire weight also increases and both could affect fuel economy and acceleration.

personally, my choices are made with all these variables and more in mind. most people don't know or care and just go for aesthetics, nothing wrong with that...

245/40 and 255/40 are sizes which fit that balanced area.

they are also running square which reduces the understeer that is inherent with staggered set ups and is another discussion in itself.

[etinifni]

Originally Posted by alohasurftoad

the factory F-series wheels/tires have a 26"-ish diameter. 235/40/18 will create a larger wheel gap and cause your speedometer to read higher than actual and odometer to accrue more mileage than actual by a small percent. 235/45/18 would be a better choice. although it is of greater diameter than oem spec it will fill the stock wheel gap a little better and cause the speedo to read right on (bmw speedos tend to read 4% higher than actual)

anytime you change from factory spec it will change the performance. typically, larger changes are more noticeable.

diameter affects final gearing which affects speedometer and odometer. overall height and wheel gap also change.

obviously there will be more grip as go wider but it increases friction drag. tire weight also increases and both could affect fuel economy and acceleration.

personally, my choices are made with all these variables and more in mind. most people don't know or care and just go for aesthetics.

245/40 and 255/40 are sizes which fit that balanced area.

they are also running square which reduces the understeer that is inherent with staggered set ups and is another discussion in itself.

So would I be better off with the 235/45 or 255/40's? Preferably I'd like to stick with 18"x8" wheels but APEX doesn't sell that size.

[alohasurftoad]

Originally Posted by etinifni

So would I be better off with the 235/45 or 255/40's? Preferably I'd like to stick with 18"x8" wheels but APEX doesn't sell that size.

you have a 328i modern line with stock suspension, correct? when you say "better off", i am not sure what better means to you, please elaborate.

either size will work and look fine. the 255 has a lot more grip obviously. if you don't drive with that need, 235's will work fine. 235's are taller and 255's have broader shoulders. both will help lessen the unsightly fenderwell gap.
245's are the happy medium but would look better if your car is lowered

you might want to consider the ps-7 or ec-7. they are heavier but look more concave than arc-8 due to spoke design.

how about a square set of 18x8.5 ET35 PS-7's or EC-7's on 235/45/18 Michelin Pilot Super Sports. still got a concave look with the best light performance tires. 43 lbs a corner.

[etinifni]

Originally Posted by alohasurftoad

you have a 328i modern line with stock suspension, correct? when you say "better off", i am not sure what better means to you, please elaborate.

either size will work and look fine. the 255 has a lot more grip obviously. if you don't drive with that need, 235's will work fine. 235's are taller and 255's have broader shoulders. both will help lessen the unsightly fenderwell gap.
245's are the happy medium but would look better if your car is lowered

you might want to consider the ps-7 or ec-7. they are heavier but look more concave than arc-8 due to spoke design.

how about a square set of 18x8.5 ET35 PS-7's or EC-7's on 235/45/18 Michelin Pilot Super Sports. still got a concave look with the best light performance tires. 43 lbs a corner.

You said the 235/40's would cause more of a speedo gap. Yes I have a Modern Line and no I don't plan on lowering it, yet.

[alohasurftoad]

Originally Posted by etinifni

You said the 235/40's would cause more of a speedo gap. Yes I have a Modern Line and no I don't plan on lowering it, yet.

i said to get 235/45 not 235/40

[etinifni]

Originally Posted by alohasurftoad

i said to get 235/45 not 235/40

I was talking about your original reply.

[alohasurftoad]

Originally Posted by etinifni

I was talking about your original reply.

yes, 235/40 will have more tire/fenderwell gap and cause slight speedometer and odometer error

[alohasurftoad]

here...this guy has xdrive with 18x8.5 and 245/40/18.

http://f30.bimmerpost.com/forums/sho...+255%2F40%2F18

[etinifni]

Matt from APEX just emailed me this:

Hello,

Thank you for the follow up email! The F30 is a difficult chassis to work with due to its limited inner and outer clearance. Therefore we do not have a concave wheel that will properly fit that chassis. Our fitment recommendation for your chassis is:

18" Staggered:
F: 18x8.5 et35/et38 Profile 1 - 225 or 235
R: 18x9 et42 Profile 1 - 255/40/18

18" Squared:
F&R: 18x8.5 et35/et38 - 235/40/18

[alohasurftoad]

Originally Posted by etinifni

Matt from APEX just emailed me this:

there are many threads and posts of members here with conservative setups like what you are planning and much more aggressive setups. i just showed you a thread of a member with a setup almost exactly what you are planning. if that's not good enough proof then i am certainly not going to stop you from following matts advice.

here's another for what it's worth
oops, never mind that's this same thread

[etinifni]

Originally Posted by alohasurftoad

there are many threads and posts of members here with conservative setups like what you are planning and much more aggressive setups. i just showed you a thread of a member with a setup almost exactly what you are planning. if that's not good enough proof then i am certainly not going to stop you from following matts advice.

here's another for what it's worth
oops, never mind that's this same thread

I was simply looking for real world experience. I appreciate your help.

[alohasurftoad]

Originally Posted by etinifni

I was simply looking for real world experience. I appreciate your help.

no problem. it's good to be informed rather than make a bad decision and purchase. i do the same research before buying anything myself. cheers...

[5hift]

i've been on the same situation before and tried to figure out the best wheel option for my F31 w/ stock suspension. current wheel and tire set up is SSR type C RS 18x8.5 et32 245/40/18 square.








currently have another set of SSR type C RS 18x9.5 et35 planning on putting on 255/40/18 on these. anyone tried this out yet?

[nadthomas]

Figured I would give an update since I started the thread. Been super busy getting my house in order before my baby comes next month, so I still haven't taken the time to snap any more pics. I did make it to 2 autocross events this summer, and daily driving on this setup. Still zero rub with my setup Apex Arc-8 18x9 ET42 with MPSS 255/40/18 on stock baseline suspension.

The location that I typically do autocross is actually a small banked circle track with a flat cross that goes through the infield. The way the first event of the season was setup the transition from the banked track to the flat infield was pretty brutal. A couple people told me on rebound at least one of my tires was getting several inches of air. So, I'm sure the suspension was getting full compressed as well, and still no rub.

Also, I have been really happy with the square setup. The 255/40 w/ the MPSS provides plenty of grip for the rear, at least for my 328i 6MT. While on course, its actually difficult to get the rear to kick around using my right foot. I'm hoping the Dinan Sport tuner I just ordered will give me enough extra power to make that a little easier when needed. Also, any less tire up front and I'm sure I would not have made a few of the faster sweeping corners this past weekend. After the first lap my brakes just weren't able to bite hard enough, so I was still under-steering like crazy.

[etinifni]

The 9.5's fit up front without spacers?

[fhlh]

Originally Posted by nadthomas

Still zero rub with my setup Apex Arc-8 18x9 ET42 with MPSS 255/40/18 on stock baseline suspension.

to confirm, you are running the 18x9 et42 up front with NO SPACER?

[nadthomas]

Originally Posted by fhlh

to confirm, you are running the 18x9 et42 up front with NO SPACER?

Correct.

[fhlh]

that's interesting... how close are you to the strut?

Reason I'm asking is I'm picking up a set tomorrow, same setup and don't want to run a spacer if I don't need to.

[fhlh]

I picked up the arc-8's in 18x9 et42 and finally got them on.
Here is a pick running 255/35 18 Dunlops. This setup required no spacers.


I picked up some new Michelin Pilot Sport AS 3+... these are some big burly tires and I had rubbing on the front strut. No worries, I brought my 10mm Burger Spacer for the front and the 12mm H&R for the rear and ended up with this setup. 255/40 Square on 18x9 et42.
I love these tires. Perfect for daily use and the ride is so much better than the RTF 19" Bridgestone setup. I'll also add that the weight difference between the ARC and 403m is unbelievable.

I like how it looks too.

[Polo08816]

MPSS 255/40/18 (which is a wide tire) on 18x8.5 ET38 will clear the front struts.

I would go with 255/40/18 instead of 245/40/18 because you have a bit more sidewall.