wheel question

hi all, i have a set of rota p1,s that i got some time ago only took old tyres off today to find 2 are 7.5 and 2 are 8.0 can i run the same size tyres on them , also wanted to fill the wheel archs with out lowering the car, can i fit 225x45s the wheels were on a honda s2000 and have a offset of 45. thanks

never said 18s