Project EP3 Si, Going 5 Lug with Wheels from Enkei and Nitto NT05 Tires

Project EP3 Si: Going 5 Lug with Wheels from Enkei and Nitto NT05 Tires

by Mike Kojima

Now that we converted our EP3 Civic from 4 to 5 lug hubs and added big brakes, there was no going back.  In order to drive the car, we obviously needed to do something about our wheel situation.  Our goal was to stuff the biggest tires we could into the stock wheel wells.  Unlike our hellaflush brethren we want big and we want traction, not stretching a narrow tire on a wide rim and stupid amounts of negative camber.

We decided to try a somewhat aggressive fitment with a pretty decently large tire and a somewhat wide wheel for a small car.  We didn’t want to have to mangle our fenders to tuck the wheel/tire combo but were not opposed to rolling the fenders.  Having experience with an RSX before we decided to try the same combination on our Civic.

To read more about Project EP3 check here!

For our Civic Si project, we approached Enkei for a set of their Iconic RPF1 wheels.  The RPF1 has aways been a favorite of ours with its clean looks and light weight. As we received the wheels, they came with this spiffy shower cap looking thing to protect the finish in shipping.

We chose the RPF1 in 17×8 with a 35mm offset.  This wheel size combo fit perfectly on several RSX’s that we have worked on before with the size of tire we wanted to run. Enkei also had a 17×9 with a 45mm offset that we were tempted to try but we were not exactly sure if that would work on our car.

The most technically advanced part about the RPF1 is its use of Enkei’s MAT technology.  MAT technology enables Enkei to economically impart some of the advantages of a forged wheel such as greater strength and potentially lighter weight with the cost advantages of a cast wheel.

The MAT process starts with the wheel’s basic shape being formed as a  high-pressure aluminum die casting.  The high-pressure casting technique removes bubbles and voids within the metal which can cause weak spots from the casting.  The high-pressure method also gives better density and grain structure than typical low pressure poured gravity casting.

In a MAT wheel, the cast blank’s barrel section is roll formed.  This is where the barrel is cold formed by spinning the wheel blank through rollers which squish the barrel section into shape under tremendous pressure.  The cold working refines the grain, adds compressive stress and establishes grain flow in the proper orientation for the stress the wheel might see in use.  The cold working of the MAT process increases the aluminum’s tensile strength due to these effects.

The strength imparted to the wheel by the MAT process allows for the wheel’s barrel section to be thinner and lighter.  It is more important for the barrel to be lighter than the center due to the inertial effect when the wheel is spinning.  Since the barrel is the part of the wheel that is most often stressed by impacts, it makes sense to take advantage of the localized strengthening of the MAT process there.

 

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