to run rear 275/40/19 on rear an 245/40/19 in front ??
for stock rims ?

 

Shouldn't be any problems but you might wanna go 275/35/19 out back. Fronts are in line though.

 

+1^ or you can try 245/45/19F 275/40/19 rear

 

You can do it, but it will make the rear tire look proportionally larger than your front given the sidewall on the rear is close to 1/2 larger than the front. Much better to run 275/35 in rear. Here is a place that is good to play with the sizes. http://www.wheelsmaster.com/rt_specs.jsp

 

Yup you should be fine, just make sure you keep the overall diameter almost the same (225/45=> 245/40 => 275/35)