That makes little sense to me. Yes the V8 weighs a little more but doubt whether it significantly alters the centre of gravity from other defenders to make roll over any more of an issue with it? I suspect it is more about excessive speed with all that weight up there….

 

it’s not the V8, it’s the fact that it comes with grippier tires. And yes, of the top speed is higher that will also play in. Basically the overall performance envelope of the V8 is such that it’s not stable with a roof load in all conditions. They could have either neutered the car back to the P400’s performance envelope (grip, top speed, etc.) or they can reduce the loading allowance to match the performance envelope they wanted to offer for the V8 model.

 

Starting to make a little more sense. It would be nice if JRL (or maybe one of the forum gurus) would have a discussion on this. Roof weight vis a vis speed, on-road/off-road, all terrain/all season tires (grip), acceleration, speed, etc. if nit from a technical viewpoint, then an owner understanding viewpoint. For example putting roof rails on should have no effect. Adding cross bars might, adding gear to cross bars likely, etc. I think we (or I hope some of us anyway) are smart enough to adjust our driving to the conditions. I would NOT go 146 mph with two kayaks on the roof on a gravel road, although now that I think about it! One thing that bugs me, any Defender can go fast with any tire, safe or not. So what’s the difference?

 

Roof load can becomes a problem at 30-40mph, doesn’t have to be 146mph. Stability with different loading conditions is a very complex problem. Land Rover is liable for the performance of the car with its factory equipment and within its stated load capacities, and they have internal requirements for what they deem is acceptable stability and how much safety factor they provide. They also have to consider what happens if the adaptive suspension fails or if a wheel speed sensor fails and stability control isn’t available.

The only thing we can conclude is that the roof load pushed the V8 defender with its suspension and tires outside of what they consider safe within their corporate policies.