According to a website I've just found they're 7.5J ET38 in which case I definitely wouldn't be running 245 as 235 is overkill for that width and offset in my opinion (and according to allot of sources, strange that Audi used tyres that wide to be honest if this is the case), funnily enough I'm about to put 225 on the exact same width and offset (although now you've mentioned this I'm actually tempted to try 235 haha).