With the pads installed and bedded in the night before, we loaded our STX wheel and tire package of choice into the back seat of the RX: 18x9-inch Volk Racing G2 flat-black forged wheels and 265/35R18 Bridgestone RE-11 extreme performance tires. Weight is the enemy in any form of motorsport, especially when it comes to wheels and tires (the whole unsprung and rotating mass thing), so we searched high and low for the lightest and stiffest wheel money could buy in a 18x9-inch size along with the stickiest 140 UTQG 265/35R18 tire (these being the maximum rim and tire width permitted in STX for a RWD car). What we came up with is admittedly a little more baller than what some budget-limited autocrossers might choose, but if you're going to break the bank at any point during a project, wheels and tires are by far the best places to do it (and you'll see why in just a second).
After doing a few warm-up laps on the factory wheels and OE-size Toyo T1R tires to get a feel for the car, we adjusted tire pressures based on the tire temperature readings we measured across each tire's contact patch. We then did a three-lap session with a best lap time of 1:29.66. This lap time was slower than we were anticipating, but our RX-8 seemed to have a lot of understeer when initiating turn-in, perhaps because of the fairly narrow OE tire size.
We then swapped on the VR.G2 wheels and Bridgestone tires and repeated this process, first doing a warm-up session so we could dial in tire pressure based on the tire temp data we collected with Enmo Racing's Longacre probe-type digital pyrometer. We then banged off four clean laps in the 1:26s, a full 3 seconds quicker than the OE wheel and tire setup. Feeling like there was still a bit more time out there, we reset our tire pressures to 39 psi front and 37 psi rear (hot pressures) and made one more three-lap run for glory. On the first lap we posted a 1:25.82, almost 4 seconds quicker than our best OE time and on the second lap traffic ruined what surely would have been a low 1:25.00. Impressive improvement, to say the least!
According to Eddie Lee from Mackin Industries, one of the leading wheel experts in the industry, "Volk Racing forged wheels like the VR.G2 provide higher camber stiffness, which really allows the tires and suspension to do their job." We also value the fact that these wheels are extremely lightweight and durable, making them a perfect fit for a street/track build like our RX-8 that needs a wheel that can survive pothole strikes on the street and curb strikes around the track. Wheels this sexy should also help us avoid striking out with the ladies, although our McLovin fake ID should help, too.
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As you can see from our tire pyrometer data, we need a lot more front wheel camber to even
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They look good in the box, but will BC Racing's coilover kit improve our RX-8's cornering
Obviously, a wider and stickier tire also helps a lot, a fact we covered in some detail in last month's Tire Review of the RE-11s. As we stated in that review, the understeer present with the OE wheel and tire setup was replaced by crisp turn-in response and impressive mid-corner grip after we bolted up our STX wheel and tire package. This translated into much higher corner exit speeds and resulted in higher top speeds down the straights. The RE-11s also provided a lot of useful feedback as we approached their limit of adhesion, making it easy to tell when too much speed was being carried into a corner. And when we did overcook a corner, oversteer was always gradual and predictable, so recovering from a slide was fun and easy.
Next we'll be bolting up a set of BC Racing coilovers to see what sort of time we can knock off our best lap at the test track, plus we've got a road trip planned to test out our suspension settings at the Seneca Lake, New York, Solo National Tour event. Come join us at this event if you live in the area!