I'm really looking to get some pro's/con's of possibly changing the rolling radius on my x when I pull the trigger on my rims and tires upgrade.

I'm going for 19x8 or 8.5 depending on the manufacturers width for the rims I choose. I want to retain a reasonable ride with a lower profile tire. I'm pondering 245/40/19 and 245/45/19. I know the 40's are the closest to stock but I'm leaning towards the 45's for the extra tire cushion on the road and to fill up the fender well a little more. Based on the calculators I used a 45ar will throw the speedo off by +3.5% (70mph = 72.45mph). I don't plan on lowering the car other than possibly attempting a sport spring swap later so I'm not worried about rubbing too much. Or should I be?

Question is what negatives will this cause beside the speedo and odometer? Have you seen older G's do this? Do you think it will look bad as in fugly? Open forum, just looking for some advice. Thanks all...

Got these screen shots from: http://www.carbibles.com/tyre_bible.html

 

2mm difference? You'll see more than that between two identical tires, one with full tread depth, and one partially worn.

 

just get 20's!