Project Emotiv3 - APEX EC-7 and Goodyear SC3

The last trip to the track was rather unkind to the car. After missing the left hand apex in Turn 6 at Thunderhill West I hit the drop before the outside curbing at the kink. This is a mistake many have made attempting to carry speed down to Turn 7, but with the stock 235/35R20 tires on a 8.5" wide wheel there isn't much sidewall to absorb an off and there isn't much rubber to protect the other edge of the wheel.

A flat Pirelli is a sad Pirelli.

Typically destroying a $400 tire with less than 1,000 miles on it would be upsetting, however I already knew the stock Pirellis were being used in an atypical fashion. There was already a set of 18x9.5" APEX EC-7 in Race Silver waiting back at the shop to mount tires on. As they say, never let a crisis go to waste. I hate breaking expensive parts and components, but I love when the replacements bring about an improved car.

Hitting the APEX

If you look around the paddock at the average track day you will find more than a few BMWs. Once touted as the "Ultimate Driving Machine", the 3-series has won the hearts of many as a fantastically engineered performance vehicle. The M3 is a car Elon Musk literally benchmarked the Model 3 against. I have run the APEX ARC-8 on my BMW M3 for many years so when it came time to choose track wheels for the Tesla I looked to the APEX catalog for help. It does not hurt that they are just across the Bay from Emotive.

Having spent time on site at APEX Race Parts before, I know that they rigorously test and certify each wheel that they put their name on. While other wheel companies might run some finite element analysis on a specific offset and spoke design, APEX takes the time to analyze every single application they release. This means the wheel you purchase has been tested as designed without any modifications such as bolt hole machining or hub material removal to reach the desired offset. Strength and weight have both been optimized for the specific wheel specifications.

APEX generally strives to have platform specific offsets for every wheel they make. Many aftermarket wheel manufacturers use a large centerbore by default and reasonably close offsets that will work on multiple platforms. In fact, this is how these EC-7 fit on the Tesla (more on this later), but their typical process for specing a wheel satisfies my inner OCD and APEX does make Tesla-specific fitments in their forged wheel lines. As the Model 3 became a more popular track car, APEX realized they already had the EC-7 readily available in a compatible size for the S550 Mustang. The Mustang shares a 5x114.3" bolt pattern, larger M14 stud pockets, and has a sufficiently large centerbore to mount on to the Tesla Model 3.

At 18x9.5", the S550 square setup also works as a square setup on the Model 3. It requires a spacer in front on the Model 3 performance and their centering rings are recommended. Because of the unique design of the APEX centering rings, they can be used both on the "base" Model 3 and the stepped hub of the Model 3 Performance. This adds an inch of wheel width over the 8.5" Tesla standard OEM wheels and even another half inch over Tesla's own Track Package wheels for the ability to amount wider tires. Wider equals more grip.

The Great Tire Debate

One of the most challenging parts of getting new wheels to me is selecting tires. How wide a tire do I want to run? Will they fit? How sticky do I want it to be? And in a post-pandemic supply chain constrained world, are they even available?

The ideal tire size on a 9.5" wheel is 255mm or 265mm. The minimum you would want to run is a 245mm and the maximum is a 285mm. Having already researched the appropriate aspect ratios for the Model 3 platform, I narrowed down the treadwidth debate. If I was going for efficiency, I might have tried to stretch a 245/45R18 on to these wheels. In fact, that may be a future use for this set as we test the limits of even wider wheels. 285mm or even wider, while doable, would result in a bulging sidewall that would not necessarily be doing its job to handle the cornering loads of the car and likely the use of bolt-on spacers to get the appropriate offset.

Settling on a 265/40R18 or 275/40R18 I started to look at what tires would be best that could be dual purpose street and track tires. While the 275/35R18 is within range and might work fine on the street, the smaller tires would hurt acceleration at higher speeds on the track where the Tesla already stops pulling hard. And as a reasonably insane person living in sunny California, I definitely daily drive 200 treadwear tires. The options were:

One tire choice stood out from the rest with an outstanding price. The Federal 595RS-PRO is a track day special with its predecessors known to be sticky and relatively long-wearing, but dirt cheap. At almost two-thirds of the price of the other tires I wondered if these would be worth a gamble, but unfortunately I was unable to find any in the listed sizes anywhere. Some sites listed them as out of stock while others listed them as discontinued. The Yokohama Advan A052s are known to be a sticky cheat code for quick lap times. This was a top choice, but neither TireRack or Discount Tire had them in stock at the time of purchase.

I then noticed something interesting about the 275 treadwear tires. The 265s of the same model carried a XL Load Range rating while their 275 counterparts were SL. XL tires feature a reinforced internal structure that can carry more weight and higher air pressures. This is reflected in their pricing as you can see a 265 Goodyear SC3 is actually more expensive than a 275 Goodyear SC3 despite needing more rubber. I noticed this on the 100 treadwear Nitto NT01 tires as well. Tesla's Owner Manual recommends that tires are replaced with XL rated tires. The Load Range is different than the Load Index which represents the manufacturers claim of what weight each tire can support. Despite the fact that all of the tires listed above have a Load Index higher than the OEM tires, a certain bit of paranoia set in on replacing XL (Extra Load) tires with SL (Standard Load) tires.

The Goodyear Eagle F1 Supercar 3 are an extreme performance summer tire originally developed for the Chevrolet Camaro SS 1LE and Camaro ZL1, a heavy high horsepower vehicle just like our Model 3s. OEM development, to me, means a high-level of testing, quality, and longevity. This is General Motor's brand on the line. I settled on the aforemetioned Goodyears as I have heard great things about their handling characteristics, other than how long they last on the street. But these tires are going to be shredded on track in short order anyhow.

Fitment Time

With tires mounted at the always great Elite Performance in Burlingame, CA, the stock Uberturbines came off and the APEX EC-7s went on. But first a weigh in.

Weigh in of OEM 20" Uberturbines with 235/35R20 Pirelli PZ4 T0 Elect.

Weigh in of 18x9.5" APEX EC-7 +35 with 265/40R18 Goodyear Supercar 3.

The OEM wheel and tire combo on our shipping scales came in to a grand total of about 215.3lbs. Our new APEX and Goodyear setup weighed in at 199.9lbs. Not only did we shave off over 15lbs of unsprung weight, we gained over 3" of treadwidth as measured by stack height. Please, please, please excuse our new ruler that does not start at 0 on each side. It went in the trash and a replacement one is on the way.

Stack height comparison.

The fitment between the new wheels and the uprights is certainly a tight one. They fit, no doubt... but I opted for a little more clearance and track width all around. These Stancemagic Universal spacers did the trick. Measured next to the APEX Aluminum Centering rings and you start to wonder how accurate our shipping scale is for very light items.

A little aluminum never hurt nobody.

While we were in there, the unsightly stock 21mm lugs were replaced with black M14x1.5 17mm conical lugs from Motorsport Hardware. All wheels were torqued to 129lb-ft and a quick drive to the supercharger for some hard parking was in order.

The new 18" wheels make for a massive improvement in ride quality. While I don't think anyone would consider the Model 3 Performance ride quality to be cloud like, the difference was felt instantaneously. The Goodyear Supercar 3 are sticky and you could hear the pebbles being picked up from the shop driveway. If you have ever had high performance tires you know this is a welcome sound of massive grip. Add to that the fact that these tires pulled up some epoxy off the shop floor and you know these will do just fine in adding to the traction of the car. Next stop? Thunderhill Raceway to test out the new setup. Happy Motoring!