ok thanks for the advice, I will keep the back tyres the same. I did start to read the detailed post on having different tyres, but as no doubtfully informative and accurate it is, I wasn't sure if it was applicable to someone like myself who was not so concerned with high speed / track performance.
regarding my "innertube" well ahem...errm yep I'm a bit dim regarding cars in general, but what i mean was whatever is used in the run flat tech to seal the tyre off.
tbh i have no idea how they work. i have just sold a 30 year old vw t2 to get this z!
its all new and exciting for me, all this performance car lark :o)
cheers for the response fellas, Im off to read wiki in an attempt to educate myself in how this beast is put together...