In my opinion, they look horrible and you have to let the rear tyre down and force it under the mudguard to get the wheel in. 350's are a good compromise. Ron
I agree, I ran a pair on my M20 for a while and I had to deflate the rear one partially to get it to fit between the end of the mudguard (with the tail piece removed) and the cross bar on the rear stand...There are also adjustment issues as described by Rob....
Additionally in my opinion, on the road it handled like a Thames barge with the wide front tyre which was also unsuitable for any off road work in 'soft going' like mud or sand..Even the 350 isn't ideal in those conditions, the narrower the better being the case then..
I run 350s both ends as I think at the front it fills the rather wide M20 mudguard better from a visual standpoint....
I try to avoid deep soft mud or deep sand when off road though......Ian