The tires sizes and air pressure recommended by Volvo for the XC90 (2003 to 2015) are:

225/70 R 16: 39psi or 270kPa on both front and rear axle.
235/65 R 17: 39psi or 270kPa on both front and rear axle.
235/60 R 18: 39psi or 270kPa on both front and rear axle.

Spare tire: T155/85 R 18: 61psi or 420kPa on both front and rear axle.

The instructions in this tutorial will work in the following models / years:
– 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Volvo XC90