hey guys im new to this forum and wanted to ask you experienced g owners a few questions.

I bought my g this mornig. it is a 2003 g35 coupe with 63000 miles.
my main question is what are the things i should be looking for as to any problems it might have? i know that a percentage of g's have an oil consumption problem.

And i had one of my friends look at it who is pretty much a mechanic and he noticed that the back tire is different from the other three. it is the exact same style but it doesnt dip in like the other three rims , i could deal with that but the main problem is that the tires are different sizes in the bvack and he said it could mess up my rear differential.

so please tell me wat u guys think. thank you