M and non-M: custom offset die forged wheels

[MBan]

On my Z4 M Coupe I'm running 8,000 tonne die forged Advan RS-DF in 18 x 8.5 +35 and 18 x 9.5 +22. These are really light (I measured them at 7.9kg/17.4lb at the front and 8.3kg/18.3lb at the rear) and super strong due to the forging process. However, I think the front offset could do with being a few mm lower to push the wheel further out. There are pretty much no options for die forged wheels in an 8.5 width (or a 9 inch) with an offset lower than +35 but not too crazy low. The only one I am aware of is the BBS RG-R which comes in a +30, but they are relatively heavy (9.2kg according to BBS and I'd wager they're actually heavier) and for the M you need to get the 10 inch rear which weighs 9.6kg. And, the BBS wheels require hub rings.

Through an Australian company that imports car parts from Japan I found out about a company called TWS Forged (not TSW!). These guys do proper die forged wheels and one of their models (the T66-F) is super lightweight and can be made in custom offsets if you buy a certain number of sets (I've been told 5 sets is enough). For reference the T66-F in an 18 x 8.5 +35 weighs 6.99kg/15.4lb and an 18 x 9.5 +22 weighs 7.97kg/17.6lb. Hub-centric, so no need for hub rings.

So, I'm wondering if anyone else would be interested in ordering a set? Prices are about 91,000 yen per wheel.

Since the Z4 M and non-M take the same wheel at the front, this is open to all Zs, but it would mean we would have to agree to a front wheel specification and then pick the rears from the standard sizes TWS do. If five M owners are keen, we could get custom rears as well, but to be honest, 9.5 +22 fits pretty well. The TWS T66-F custom menu has some really nice custom colours, but if we pick an off the shelf rear wheel (colour and offset), we would have to pick the same standard colour for the custom offset fronts.

Over the last couple of months I have been testing a bunch of different front offsets using spacers. Effectively, I've tried 8.5 +23, +25, +27.5 and +30. I've done some heavy cornering and got quite a bit of rubbing on the arch liner (to the front of the wheel, where that little round push clip joins the liner to the guard) with the +23, a bit with the +25 but was fine with the other two offsets. For reference, I'm on KW V3s, 10mm lower than stock at the front, -2 degrees of camber, 235 40 R18 tyres and I used a heat gun on the arch liner to free up a couple more mm. Based on this, I'd be happy with an offset of +28 or 2mm either side.

Here is the T66-F page (sorry - it's in Japanese):
https://www.tws-forged.com/tws_t66-f.html

And here is the 'custom' page:
https://www.tws-forged.com/tws_t66-f_custom.html

Finally, here is a Youtube review:
https://www.youtube.com/watch?v=ge8QjcaqpP8

[MBan]

I just checked the Rays Japan website and there is now effectively no direct fit Volk wheels for Z4Ms unless you can fit a 9inch +23 wheel on the front, which is pretty aggressive. I'm not as familiar with non-M fitments but in general 5x120 with a 72.6mm centre bore is pretty much only available in M2 fitment.

Advan seems to be going the same way, although I think they do still have a couple of wheels that work.

The second hand market is pretty variable as well. I check Yahoo Japan every couple of weeks and see virtually nothing in our specifications.

I don't want to be over-dramatic but very soon it will be impossible to buy direct-fit wheels for our cars that are made to the highest specification (i.e. 8,000 tonne die forged). I'm planning to keep my car until I can't physically get in it anymore, so that's a sobering thought to me.

[86Zed]

Originally Posted by MBan

I don't want to be over-dramatic but very soon it will be impossible to buy direct-fit wheels for our cars that are made to the highest specification (i.e. 8,000 tonne die forged). I'm planning to keep my car until I can't physically get in it anymore, so that's a sobering thought to me.

I recall hearing about TWS when I was researching wheels for another car. JDM wheel companies have never had the best Euro fitments especially for a low volume car like the Z4.

Pardon my ignorance, but there are still a few brands doing BMW Z4M fitments with quality methods? This list is not all inclusive, I imagine BBS and HRE have solutions as well.

https://titan-7.com/
10K die forged methods used

https://www.apexraceparts.com/
10K die forged offerings (in addition to cheaper methods)

Both companies offerings are used extensively in grassroots Motorsports here in the USA.

[MBan]

Originally Posted by 86Zed

I recall hearing about TWS when I was researching wheels for another car. JDM wheel companies have never had the best Euro fitments especially for a low volume car like the Z4.

Pardon my ignorance, but there are still a few brands doing BMW Z4M fitments with quality methods? This list is not all inclusive, I imagine BBS and HRE have solutions as well.

https://titan-7.com/
10K die forged methods used

https://www.apexraceparts.com/
10K die forged offerings (in addition to cheaper methods)

Both companies offerings are used extensively in grassroots Motorsports here in the USA.

Sorry - I didn't realise Apex and Titan 7 used die forging! The offsets available are another matter but I'm prepared to admit that what these companies offer will suit many Z4 owners. HRE and Forgeline will obviously make pretty much any offset, so they are an option.

As far as I can see, BBS doesn't have many options in an 18 inch wheel. RG-Rs are available in an 8.5 +30, which is pretty good, but that's as close as I think they get unless you count a custom spec in an E88.

Anyway, I think I'm getting a bit paranoid about options for our cars drying up!