Chaps, anyone have experience with running 13" wheels on a Westfield SEIW?

I currently have 15" 8J ET23 wheels running 195/50 Toyo T1R. my dilemma is whether I just change tyres (T1R is lethal in the wet) or wheel tyre set up to 13" 7J with 185/60 front & 205/60 rear R888R's (Eugene ;)).

At present I'm not sure if some of the handling issues are due to too much stretch on the tyre (it feels as if the tyre works on a narrow band in the wet & just drives off the sidewall) & whether 205/15's all round would remedy this, would this make the front end too heavy? or should I just go for 13"s

My other concern is whether there will be sufficient clearance for the bell housing loop or whether this would have to be modified.

I have trawled the forums for answers but as usual there are too many conflicting opinions, a common theme seems to be that people like 13" 7J with 185/60 front 205/60 rear

Any advice is appreciated