just like the title states...is there any detrimental effect if i switch?

 

The diameter difference between 275/35/19 and 275/30/19 is more than 4%. Its recommended that the size variance doesn't exceed OEM by more than 3%. Your odometer will run fast, and you might run into VDC issues depending on the size of your front tires.

 

You DO NOT want 275/30. Stick to 275/35 or 285/35, as long as your rears are is between 9.5"-11" wide.