M/T's ET Street Radials carry...
M/T's ET Street Radials carry Part No. 3743R and measure 275/40R17. Touted as the world's fastest street radial, the ET Street is a D.O.T. approved street legal drag radial. The polyester ply, steel-belted radial has a directional tread pattern and is recommended for maximum dry traction (no rain). With a diameter of 26 inches, the company recommends mounting them on 8-10-inch wide rims.
The stock GTO 5-spoke aluminum...
The stock GTO 5-spoke aluminum wheel measures 17x8-inches and has P245/45ZR17 BFGoodrich G-Force TA KDW tires from the factory. It has a 5x120mm bolt circle and 48mm offset. Converting the millimeters to inches yields a 5x4.7244-inch bolt circle. Note the prominent inner fender lip on the rear wheelwell. When mounting any 17-inch tire wider than a 255/40-17 onto the stock rim, the chances of cutting the tire on the inner fenderwell are great.
When released to the public, the newest generation of GTO quickly became known in automotive circles as one of the most refined platforms to hit the U.S. marketplace. A true performance coupe by any definition, the Goat offers impressive handling, ride characteristics and stellar performance.
Achieving maximum acceleration and obtaining the ability to push the car harder through the turns, however, is hampered by the OEM design of the front and rear wheelwells that leave little room for larger wheel/tire combinations. From the factory, the standard 5-spoke aluminum GTO wheel (PZ9) measures 17x8 (43.2 cm) and is shod with BFGoodrich P245/45ZR17 G-Force TA KDW tires (there was an 18-inch wheel option, as well). Mounted on the stock rim, the section width of the tire is 9.6 inches with a diameter of 25.7 inches. Clearly, a larger rear tire would help in the quest for better acceleration, but how can this be accomplished without having to perform surgery on the rear wheelwells of the GTO?
Seemingly from day one, hobbyists have been trying to stuff the largest tire possible under the GTO, creating a dizzying array of choices. By far, the most popular one out there is to purchase a drag radial in a P275/40-17 size, mount it on the stock rim and then roll the rear inner fender lip to provide enough clearance so that the lip doesn't come in contact with the tire when the car is either launched at a dragstrip or driven aggressively on the street.
Although most tire manufacturers say that the acceptable practice is for rim width to be plus or minus 1 inch from their optimal recommend-ation (which is 9 inches for M/Ts radials), mounting a P275 tire on an 8-inch rim forces the sidewall to "pooch" out, effectively shortening the overall mounted diameter of the tire, so we prefer to go with the 9-inch rim.
If that's not enough, although the rear inner fender lip may be rolled with a specialty tool, you risk damaging the body in the process, and you are lowering the potential collector value of your GTO.
Is there another way to get wider rims and fatter, stickier tires on your GTO without performing surgery on the body or breaking the bank? Follow along as we modify ($75) and install a set of used 17x9-inch WS6 wheels, ($200 for a pair) shod with Mickey Thompson's 275/40R17 ET Street Radials ($189 each). A set of BMR's GTO drag bags ($99.95) will be employed as well to keep the wide tires away from the inner wheelwell lips on the '06 GTO owned by Bob Cook from Allen, Texas. Other than a custom dyno tune (HPP, July '07), the automatic equipped car is stock. Now let's get to it.