what size speakers does the scion xb come with

it should tell on the website, or call bgest-buy car audio and they will tell you.

5in

5.25 in ,for all the doors,
also check this link for more info
http://scionlife.com/forums/viewtopic.php?t=64509 good luck

In the '03-'06 xB the tweeters are 1'' in the dash. The front doors are 6.5'' and the back speakers are 5.25''

In the '08 xB the tweeters are 1'' in the front door, the front doors are 6.5'' and the rear doors are 5.25''

There are also several mounting kits that will let you fit larger speakers into the door for the '03-'06 xB.

Hope this helps.