Sorry in advance, don't crucify me too much. I know ZERO about tires.

Can someone tell me how on stock sport 19" rims front and back you can fit 245/40 on the front and 275/35 on the back? I understand that the diameter of a 245/40 for front and 275/35 are the same as the stock bridgestone tires, but how can they be mounted on the stock rims because the widths are different? Is there a certain amount of "stretch" that can be applied when they mount them? Thanks in advance.

 

Yes you can.

 

Yes, a given wheel width can accommodate a range of different tire widths.

 

yeap, its called "Plus Sizing" and with the 245/40 in front and 275/35 in rear its called a "Plus Zero"
cuz like u said... the overall diameter (OD) is unchanged.