Bigger in the rear

The widest I'd consider going with the stock 16x7 pony wheels is a 245/50/16...Anything wider is going to look like a balloon.....but with a 9" wide wheel, you could get away with a 275mm tire with little issue.
 
The widest I'd consider going with the stock 16x7 pony wheels is a 245/50/16...Anything wider is going to look like a balloon.....but with a 9" wide wheel, you could get away with a 275mm tire with little issue.

yup, just take a look at the 255 bfg drag radials, they bulge seriously on a pony rim.
7 inch are pretty narrow by todays standards.