Bogie (Truck) Wheel Base
 

Why do some Aircraft have such a wide wheelbase on the bogies (Trucks), like the A350 for example? It means much more space required in the landing gear bay, less even loading on uneven ground, more torque during turns. I can think of no single positve aspect. Obviously there is more than enough space for brakes.
On the Comet for example it was very narrow (as it was stored in the wing), did this create issues?

Having a wide track must reduce the chance of it overloading and breaking the pavement, which is probably a great benefit.

The wide wheelbase reduces the load on the pavement. I just checked it now, using the bogie undercarriage for a C141 which I have in my design system. Extending the wheelbase by 300mm from the standard 1427mm to 1727mm dropped the ACN on a ‘D’ subgrade from 66 to 59. The effect is less on stronger subgrades. (A/c weight 142.9 tonnes).

Airbus have a three-pronged main undercarriage design philosophy encompassing both four- and six-wheel bogies to ensure it can keep the pavement loading within limits. The A350-800 and A350-900 will both have four-wheel bogies, although the -800's will be slightly shorter to save weight. Both will fit in the same 4.1 m (13 ft) long bay. The proposed higher weight variant, the A350-1000 and the A350-900R will use a six-wheel bogey, with a 4.7 m (15 ft) undercarriage baytrack.

The Comet weighed 50-71 tonnes, and the A350 weighs 259-308 tonnes, so the Airbus people have a lot more weight to contend with.

On the A300B-4, IIRC Eastern Airlines had the Main wheels on longer axles than other operators. This was known as La Guardia gear presumably due to lower pavement strength at that airport. The gear doors had small blisters to allow for the wider spaced wheels.