Check the plastic lining on top of the wheel arch adjoining to the guard, theres a few tabs there that you can push back to get some clearance that usually helps
firstly yes its illegal,
secondly depending on the quality, i've seen it where the slip on adapter over time compresses making your tightly torqued nuts not so tight anymore.
and if they are not...
I know im a trader on here and im not trying to plug, but it still amazes me how people pay ridiculous prices for tyres when they can get the same product for much...
There's tyres other users have tried like toyo t1r, dunlop direzza dz101, Bridgestone potenza re050. Depends on your budget and what you want from your tyres i guess.
if your already on your fulls dont bother with a cbr250rr. They are waay overpriced becuase they are LAMS approved. i mean you could get yourself an earlier model 600 for similar cash