D.I.Y.: Wheel Spacers on a G35 sedan

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Wheel Spacers on a G35 Sedan

Thank you for having me as a guest blogger! I recently installed wheel spacers on my 2006 G35 sedan, and I'll take you through my thought process and some of my considerations.

Figure 1: Overall Pictures of Before and After.

The Problem: 

Wheels looked odd with a "tucked" look after lowering the suspension by about 1.25" from stock height. Normally I don't care too much about pure aesthetics, but it was enough to annoy me into looking for a solution.

The Options:

1) The best option is always to get a set of wheels with the proper width and offset to suit your application and tastes. 

Normally I would go for this option, but I actually really like the look of the stock 18's, I prefer using OEM wheels, and I just purchased new tires, so I wasn't about to spend $1000+ just to get a nicer stance. My current setup is 18x7.5 +45 offset with 235/45/18 tires. If I was starting from scratch (i.e. car sitting on blocks), I'd get a set of lightweight 18x9 +30 offset, running 255/40/18.

2) The next best option is to widen the track with the use of wheel spacers. This is what I used. I will say that there is a lot of negative hype about wheel spacers, and for good reason. After doing a lot of technical reading, I've come to the conclusion that concerns are generally well founded. A lot of the horror stories result from people not using common sense. However, spacers can be used safely (and they are, even on AutoX courses and on the track) if you know a few key things:

   a) They must be "hubcentric" spacers. This properly locates the axis of rotation between the wheel, spacer, and wheel hub by means of features on the spacer which aligns all three components. The diameter of the spacer hub should match the wheel hub and wheel exactly (female on one side, male on the other). This is a much more reliable way of getting everything lined up properly compared to relying on the lugs to get everything centered. The consequence of misalignment is tooth-jarring vibration at high speeds.

   b) Proper studs should be used. For those with smaller spacers (5-10mm), this likely means removing your factory studs and replacing them with longer ones. For larger spacers (15mm+), this means using spacers with studs already attached. 

Drawbacks to Spacers:

1) Increased scrub radius. This is the same problem that would result from using the same width wheel/tire but lowering the offset. The axis of rotation from steering movements is no longer in the center of the contact patch. The major symptom is the increased effect of 'tramlining,' which is the phenomenon of your tires wanting to grab and follow features on an uneven road surface. More on this later.

2) Increased wear on wheel bearings due to lengthened lever arm. Again, this is a problem that is shared with reducing the offset of your wheels. I view bearings as wear items, and if I have to replace them 10% sooner - so be it!

3) Increased rotational inertia and unsprung mass. This one is unique to spacers, as using wheels with a different offset does not inherently add any mass. The extent of the effects is usually not noticeable, as the spacers are made of lightweight 6061-T6 aluminum alloy and the weight is added close to the axis of rotation. I personally did not notice any dynamic differences from the result of adding this weight.

The spacers I used:

I picked up 25mm hub centric spacers with integrated studs, made by a company called Precision European Motorwerks. The studs secured in the spacer are Metric 10.9 studs (equivalent of Grade 8 bolts), and the spacer simply bolted to my wheel hub with the supplied M12 nuts:

Figure 2: Spacer Install.

I initially found them on Amazon for ~$62 a pair and they had good reviews. I then checked eBay to see if they listed there as well, and sure enough they were - and for only $55 a pair! I purchased two pairs, and they arrived at my house in just two days. There are many "brand name" options out there, but lets face it - they are all just machined aluminum. As long as you trust the quality of the machining, all of the hubcentric spacers are going to be about the same.

Installation:

They installed without issue. Before bolting on, I checked for play between the spacer and the hub and also between the spacer and the wheel. It was dead nuts on. The diameter spec was almost certainly within 0.001". The quality of the machining was excellent. No problems trusting the supplied metric 10.9 grade studs.

I applied copper anti-seize lube to the back face of the spacers and to the OEM studs since I probably won't be touching them again until I need to replace my rotors again. Tightened to 85 ft-lbs. I used a 2x4 and the power sliding seat to keep pressure on the brake pedal while I tightened down the fronts.

The rears came out a little further than I was expecting, so I had to roll the fenders a bit. Used a heat gun and a 2" SCH40 PVC pipe, about 2.5' long. Each side took about 20 minutes to roll and was relatively painless.

Impressions:

For the most part, the spacers are not noticeable at all from the driver's seat. I was certain that widening the track by 2" would have a tangible effect, but I have not noticed it at all in the month I've had them on so far. I also did not notice the effective decrease in spring rate by the lengthening the lever arm. I have noticed some of the tramlining effect, although I'm unsure if that is just due to my heightened sensitivity to this.

The biggest difference is just in the stance - the way the car looks. My goal was to improve the look of the stance, and these spacers achieved that goal without hurting my wallet. Mission accomplished!

Figure 3: Front Wheels before & after.

Figure 3: Front Wheels before & after.

I often find myself doing double-takes on my car now as I'm walking away after parking. An unknowing observer would probably be wondering where the hot girl is hiding that I keep turning around to check out.

Best,
Guest Blogger.