I would go for the 225 as theyre just for Track and as i know from my last Car how Anneau is to the Tyres the more wide version can suck up more heat. So go for the wider ones i would say. (If the Price is OK, seen prices in CH about 30 CHF more for the 225s over the 215s )
But yeah, thats why i have to get Track Tyres first, Friend got at AdR with his Type R on Road Tires.. after 2 Laps they where peeling and sticked like... slime on a window
Oh, and go for the GG or GGG version as the more soft the more Grip, but at Anneau Conditions they will wear alot more faster when theyre softer. And at least i am not after the times but the fun, so the harder they are the longer you can run on them... but well, i think thats common knowledge
Here is a Swiss HP who sell them obviously, bu not the 225/40 version, but probably the 235 will fit, but im not sure because the semis are always wider in real than road tyres...
Also you should call your local Pneuhaus probably, last time i just called a random one here and theyve got me 4 205/50/15s in GG for 660 CHF incl. Mounting and so on...