Originally Posted by 
PeterM
				
			 
			Wider is not necessarily better as you start to encounter issues with 'tram lining' on the road and not being able to get the purchase you want off-road due to the way the tyre contacts the ground. If you're doing mud runs, great. If you're doing other things then consider something more appropriate.also good at bending steering linkages
Since the gearing is stock I strongly recommend 245/75 R16 as the size to go with for general use and medium off-road use. They are a 31" OD and a very good match for the vehicle.
unless you are willing to spend $$$ and hours to make 33's work Peter has hit it with this one
235/85 R16 work well as a 32" tyre. This is the stock size on the Defenders and you can run them on std rims with no I'll effects. Camel cut to the rear wheel arch and suspension lift are all that is required.
for my first few years of owning the disco I ran this size for off road and stock tyres for daily driving - manual gearbox sucked(IMO)but auto's handle it well apparently
Wider tyres cost more to buy and you'll increase your wind resistance as well. Fitting the spare also starts to become as issue as 245 is as wide as you'll get on the stock mount.
offset rims changes that number, 285/75/16 on -25 offset fits fine