For those who have Jag 18's...
How would a 245/40/18 front and 255/35/18 rear compare overall diameter-wise to the stock 235/50/17. I know they are wider, but are they as tall or taller? I do not want to put smaller tires on my car...

the 245/40/18 is ok, but you will need at least a 275/35 or 275/40 for the rears to be the same diameter as stock.

I have 245/40/18 and 275/35/18s, they are ok, but look a little small, especially if the car is not lowered, once lowered they are ok. When I'll be changing em again, I'll go with 245/45/18 and 275/40/18, or maybe I will keep the 245/40/18 in the front and go 285/35/18 like 02V8Sport does. Don't know yet.

The set of Jag rims on Ebay got cancelled early, before I could snag them...
I just wanted to know if the rims/tires were the same overall diameter as the stock ones, or at least really close.

Yep, they are close.

Man, If you can score a set of those wheels it will look great. I saw Hylifes car on the freeway and it is sweet.