Main Gear on 777 and A340-600
 

Can anyone shed some light on the following questions:

What is the theory behind the A340-600's main gear design (left and right mains are standard bogey trail, with an opposite arrangement for the centre main)?

Why did Boeing opt for the 6 wheel arrangement on the 777 vice a centre gear similar to the A340-600?

Thanks in advance.

I didn't take part on the design of eighter machine, but my educated guess is that it was a historical decision:

A340 had initially ony a 4 bogeys main wheel, then larger series came on stock. To have commonalities as much as possible, they continued the bogeys and added some more wheels.

The 777 was a new design, so they could figure out that it was the best/lightest/most strongest design with 6 bogeys.