Sloping driveways and GTVs / Spiders
As promised I have carried out a study based on some models and ACAD 3D drawings.
Seems that for a standard GTV a slope of 1 in 4 is sufficient to clear. i.e. for every 1m depth the slope must be 4m long.
However if one has a Zender kit, the slope should be at least 1 in 5.5 or 1 in 6 i.e. for 1 m depth the slope is 6m long.
Calculations are based on standard ride height - so if you have lowered your car further, the slope is even greater.
hope you can find this info useful.