It reduces side wall flex for purposes such as drifting, making the slide more predictable and easier to comense. Hipari style also increases handling. And according To REVspeed magazine which is definately one of the best technical magazines. a test was done on this concept. And it was proven that Hipari style gives the drivers better track times. I dont undertand why people have such a negative outlook on this, when it only improves yur drivabilty and performance of the vehicle.

Just for reference....

ReVspeeds findings.

The first set they used would be what you would recomend. 235/40-18 on a 18x7.5 wheel.
The track times came out to be 1'03.369

2nd set 235/40-18 on a 18x8.5 wheel.
The track times 1' 03.103

3rd and final set was 235/40-18 on a 18x9.5 wheel.
The track times 1'02.680