Jun 12, 2020 update to the BMW M3 project car

Project BMW M3: Spacers and Square Wheels for Our E46

Why are we wheel shopping? Because it’s fun. (Come on, admit it.)

A more practical reason: We wanted to move to a fully square setup on our 2004 BMW M3. Although we were running the same tire sizes at all four corners, different wheel offsets prevented us from rotating front to back.

How do you run the same exact wheel spec at all four corners to create a fully square setup on an E46-chassis BMW M3? With wheel spacers.

We know, some of you just made a face.

Something to think about: The factory-built, factory-developed BMW M4 GT4 currently campaigned by BimmerWorld and many others features wheel spacers over 30mm up front. For real. Photo below:

And, here, we made a meme.

Let’s get back to the start of this little odyssey: What size wheel for our E46-chassis BMW M3? Today’s market offers many options. 

So we pinged BimmerWorld, where Austin Via is the in-house wheel expert. He filled us in regarding sizes and introduced spacers to the equation. 

His advice:

For a street car that sees some track time, I would recommend two setups. 

1) 18x9.5 ET 35, squared, with a 12mm spacer in the rear. This setup is our go-to street fitment that fits well and looks good with minimal to no camber. 

2) 18x9.5 ET 22 squared. This is a nice setup for people who would rather add camber than run a spacer. 

Upon hearing that our car has 2 degrees of negative camber up front, Austin steered us to the setup featuring the 35mm offset wheels. “That amount of camber sounds perfect for the 18x9.5 ET 35,” he said. “Pair that with a 12mm spacer in the rear and you have an awesome setup on your hands. Run a 265/35R18 tire all around. That is more than enough tire for the car and a great size when it comes to your available options.”

Now to further refine our search: We also wanted a wheel that didn’t require centering rings. We’ve run centering rings before, and we’ve fought with them, too—we’ve had plastic ones melt and metal ones stick to the hub. We realize, though, that they allow wheel manufacturers to cover multiple applications with one casting. But maybe this time we could bypass them. 

Why does the center bore of the wheel even matter? Studs provide clamping force, explains BimmerWorld’s James Clay, while the vertical load is placed upon the center of the hub. A hub-centric wheel—one where the center bore matches the BMW’s hub—would eliminate the need for centering rings.

We also wanted a wheel that was lightweight, so we started looking at the forged offerings—really strong yet a lot lighter than other options, making them the golden answer when it comes to wheels. There’s a reason why pro teams use forged wheels, right? 

A negative to forged wheels? They can be pricey—like, for our application, maybe $3500 per set to more than $1500 per wheel. 

Somewhere in the decision process: Looks matter, too, right? 

While doing our research we noticed a Titan 7 ad in a magazine called Grassroots Motorsports. The company’s tagline: Forged for all.

The pitch? A lightweight, forged aluminum wheel for right around $2000 per set. How so?

According to the website: “The key to Titan 7 Forged Wheels is that we make all of our wheels in house. Everything from design, tooling, forging, machining, heat treatment, surface finishing, and testing is all done in house. Very few forged wheel companies can make this claim. This means you get complete quality, performance control, and efficiency.”

We noticed some other things that would keep prices down. For one, there wasn't a ton of part numbers. Titan 7 currently show six styles—four for cars, two for trucks. And no custom work. Each application is offered in a limited number of colors. 

Something we learned from our friends at Paul Reed Smith Guitars: Fewer SKUs in a model line—meaning fewer possible combinations—can help lower prices, as it simplifies the entire operation. The Titan 7 process: Pick a model, pick an application, pick a color. In some cases, multiple sizes might be offered, but it’s a rather streamlined process. The company's site even shows whether or not the wheel is in stock—so, not just forged for all, but forged for all rather quickly, too. 

Some more facts about these wheels that we learned from the Titan 7 site: A knurled bead seat prevents tire slip, there's lots of room for big brakes, and very detailed machine work minimizes weight while maintaining strength. 

Here’s where we went a little off the menu. The Titan 7 site recommends a 22mm offset for our application, but we decided to take BimmerWorld’s advice and go with a 35mm offset. Titan 7 offers the 35mm offset for other BMWs, so we’d still wind up with the proper 5x120mm bolt pattern and 72.56mm center bore. 

Titan 7’s T-R10 wheel, a 10-spoke model, covered all of our desired specs. Listed weight is 18.7 pounds. One question, though: Machine Black or Satin Titanium? The latter got the nod. 

Spoiler alert for the next update: We'll talk a little more about those wheel spacers and bring studs into the picture. Then we'll need to shop for tires. 

 

Join Free Join our community to easily find more project updates.
Comments
View comments on the GRM forums
dean1484
dean1484 MegaDork
6/11/20 8:40 a.m.

I don't know anything about BMWs but could you have used a set of spacers to Rotate the stock wheels?  

Olemiss540
Olemiss540 Reader
6/11/20 9:34 a.m.
dean1484 said:

I don't know anything about BMWs but could you have used a set of spacers to Rotate the stock wheels?  

Stock wheels are staggered.

wspohn
wspohn Dork
6/11/20 11:33 a.m.

How many miles do you expect to put on this thing?  Tires may well age out before they wear out anyway.

If you run directional tires you aren't going to be able to rotate side to side much less front to back anyway.

codrus (Forum Supporter)
codrus (Forum Supporter) UberDork
6/11/20 11:47 a.m.

I've got 18x10+25s on all four corners of mine without spacers, but it's a full track car (cage, etc) with lots of camber.

 

David S. Wallens
David S. Wallens Editorial Director
6/11/20 12:04 p.m.

In reply to codrus (Forum Supporter) :

Yeah, with more camber, we would have had more clearance. Did you have to roll your fender lips? And what size tire are you running?

David S. Wallens
David S. Wallens Editorial Director
6/11/20 12:06 p.m.

In reply to wspohn :

Good question on how many miles. Mainly looking to maximize tire life considering some track events.

Keith Tanner
Keith Tanner MegaDork
6/11/20 12:12 p.m.

One of the things to do on the E39 M5 is put a set of rear wheels on the front. I think you need a 3mm spacer. Cuts down on understeer, looks badass and lets you rotate tires. Also, it looks badass. 

Of course, there are repros of the front wheels but the only source for rear wheels is take-offs and salvage. They're stupid expensive, it's cheaper to buy a new set of 4 aftermarket wheels in the same size than a banged-up pair of OE rears.

Slippery (Forum Supporter)
Slippery (Forum Supporter) UltraDork
6/11/20 12:23 p.m.

In reply to Keith Tanner :

That's what I run on my e46 M3, four rears. I have 10mm spacers in the back, but none are needed. 

The main problem is that the factory wheels are HEAVY. I have a different set of wheels for track work so I dont mind the weight. 

codrus (Forum Supporter)
codrus (Forum Supporter) UberDork
6/11/20 12:29 p.m.
David S. Wallens said:

In reply to codrus (Forum Supporter) :

Yeah, with more camber, we would have had more clearance. Did you have to roll your fender lips? And what size tire are you running?

The fender lips are rolled, yes.  I have 275/35R18 NT01s on it.

ZOO (Forum Supporter)
ZOO (Forum Supporter) UltraDork
6/13/20 7:31 a.m.

In reply to Slippery (Forum Supporter) :

I ran a square set of the OEMs, too.  I didn't ever go wider than a 255/35/18.  Then I went to Apex ARC-8s . . .

I currently run a square set on the M2, as well,  It simplifies track day costs to be able to rotate tires as needed.

Sponsored by

Bimmerworld

Our Preferred Partners
ZkBDKMr6lXkWeLuSZlI57g7W98RS2wAbUfN9ESwsUSzmqe4h6eAJSWh0eIP6a0UJ