Proper rim upgrade size for M roadster

[DimrBimmer]

Hello to all. I am getting my recently acquired 2001 M Roadster slowly ready for spring, one small part at a time. Should have been posting in "what did you buy your z3 today"... anyways, I am currently running stock 17 staggered m rims and want to upgrade to 18 and want to know how wide I can go in the front and back with stock suspension. Including offset. I might or might not be replacing to Koni shock absorbers as well. Car is going to be for some mild track days and street. Want to get wider rubbers on to get better traction on the track. Any recommendations for size and offset? Thank you in advance.

[DimrBimmer]

I have an opportunity to pick up
18x8.5 ET 35 front and 18x9.5 ET 45 rear VMR rims
Or another bimmer replica brand 18x8 and 18x9 both are ET 35.
I am wondering if that rear offset is way too much the the wheel well or the spacer required would be way too much. Any suggestions, recommendations?

[rf900rkw]

Do you consider a 30-40mm spacer too much? I do.

[DimrBimmer]

Do you consider a 30-40mm spacer too much? I do.

I absolutely do. Unless I only drive in straight lines . I am just trying to confirm. This is new hobby for me and I am just using common sense, not educated fact...

Thank you for confirming.

I did watch a video that talks about using spacers is not good all together. I assume that that is not 100% true statement and small spacer is ok. Would you say that I should not get rims with offset that requires more then __ mm? (If I would guess, if I am tracking the car I should probably not go over 10mm, but I have no clue). I also understand that tire needs to fit inside the well. Hence, this post to get an idea what some others are using on their m body.
Willtheyfit.com comes handy too

[PbFut]

You are on the right track. Wheels for our car are difficult to find in correct configurations.
If your are going to track, invest in studs.
The Apex wheels are probably your best option but the 17x10s are often out of stock.
Buy wheels that are easy to replace in single unit orders. Bending wheels, especially when you are learning is very common and you want to be able to replace with a few mouse clicks rather than waiting 6 months or a year for the vendor to restock. (Apex 17x10 were 18 months at one point.)
I have used up to 15mm spacers on track with race rubber and zero issues for over 15 yrs.
The hubs have studs and I am very cautious about making sure both the spacer and wheel are correctly seated prior to torquing down. Always with a torque wrench set to 85ftlbs. They say replace studs yearly. I do every 5. But then again, I am careful with use.
18in wheels are easier to find and look the best in my opinion. 17s are less costly in tires but you have far less options both in wheel and tire availability. I run 17s because of cost and I have 5 sets that would need to be replaced. I sort of wish I had gone 18s in the beginning but I can say I've saved a bucket of cash in tires by running 17s. Trying not to offend, 19s are just too big on the car for my taste. I hear others that would have nothing else. If you track and use 19s, you will not like the expense and the added MOI weight will be a big disadvantage. Do not run 19s on track unless thats all you got. Light weight wheels are very noticable on track. But tend to be weak unless you invest in custom units at >1000 each. I have collapsed my share of light weights. So I tend to baby the lights I have and the 2 heavy sets get the duty when I am in the mood to dive like a Australian. (Super Car style) Hope this helps some. I did not go into sizing as that depends on intended use, suspension options and willingness to F with the front wheel body work.
Best of luck.

[MartyBtoo]

I kept some notes for a very conservative set of Apex wheels for my M Coupe. Fronts were18x8.5 ET38, rears were 18x10 ET25. This setup had lots of clearance to the wheel wells and didn't require adding camber to clear.

Marty

[DimrBimmer]

I kept some notes for a very conservative set of Apex wheels for my M Coupe. Fronts were18x8.5 ET38, rears were 18x10 ET25. This setup had lots of clearance to the wheel wells and didn't require adding camber to clear.

Marty

Thank you Marty. Did you have aftermarket suspension, or stock? And no spacers, correct? Also, what size rubber did you use to clear the wells? Based on my calculations 265/35-R18 for rear and 245 or 235/35-R18 front?

[MartyBtoo]

Mine is Koni shocks with stock springs, and 265/35 rear and 245/35 fronts. Or if I felt like it, 275/35 rears and 255/35 fronts; with the roads I have out in the boonies, I tend to like a slightly taller tire.

Marty

[rf900rkw]

I have what is likely the limit of what can be fitted under stock fenders and liners. I am lowered some, and do have flipped hats.

17x9et38 255/40
17x11et19 315/35

[deni2s]

I am lowered some, and do have flipped hats.

Flipped hats? Can you elaborate more on that?

[rf900rkw]

M strut tops (hats) are slightly offset. By switching left to right, you gain about 1.5 degrees of negative camber.

[deni2s]

M strut tops (hats) are slightly offset. By switching left to right, you gain about 1.5 degrees of negative camber.

Thanks! I know some people are even rotating them around to get different camber options.

[BimmerBreaker]

Thanks! I know some people are even rotating them around to get different camber options.

I don't think they should be doing that. Rotating side to side just changes the camber, rotating them willy-nilly will change other settings too

[Harvey Mushman]

I have what is likely the limit of what can be fitted under stock fenders and liners. I am lowered some, and do have flipped hats.

17x9et38 255/40
17x11et19 315/35

Do you have any more pics besides the one in your signature?

[s8ilver]

I'm running these 18s on Z3M...but I could fit wider out back for sure. I rub the front fender liners ever so slightly on an exuberant bumpy corner. Hats are not flipped. I'm also lowered on H&R springs. Tires 235/40 and 285/35.

https://www.apexraceparts.com/shop-b...s-7-wheel.html
https://www.apexraceparts.com/shop-b...s-7-wheel.html

I got tired of researching what options I had, and went with this article as my guide and called it good.

https://www.apexraceparts.com/blog/p...mw-z3-m-coupe/

[rf900rkw]

Do you have any more pics besides the one in your signature?

The Sig pic is ten years and several setups old. In the pic are Rondells at 17x8 et38 and 17x10 et15.

There is a pic of the current setup in the "other cars" thread. I can repost it hear once I at the home computer.