I'm running 225/40/18's on my 9.5's now not dangerous at all as long as you pick a tyre with a well reinforced sidewall. Plus its the only way I can tuck my wheels under the rolled guards.
Dean, take it over to Driftline in campbellfield, one of the guys there should be able to stretch them on (although, 245's aren't really that much of a stretch, we usually do 235/40/18's... they tend to be closer to the overall rolling diameter of a skyline wheel so it doesn't put your speedo out, plus the tyres are cheaper to buy). Usually its the bicycle tyre method we use, makes for a lot of fun and shenanigans too when its done.
That said, unless you're riding dirty (ie you need to tuck tyres under guards), you should just fit something that fits under the guard and is easier to put on.