so im running stock tires with aftermarket rims and want to get some spacers so they sit flush with the fenders but i dont know a lot about spacers and am not sure what size i would need?

You're going to need something in the realm of a 20-30mm spacer to even get close. Stock wheel size is 17x7 with a +45 (+47?) offset.

you can use this chart and some basic math to help you out: http://scionlife.com/forums/showthread.php?t=142934

also try doing a search..this has been discussed a few times.

im runing 25mm rear spacers and 20mm front spacers,and i get a perfect flush lookin,im on stock rims but aftermarket tires

We need more information about your offset for the aftermarket rims.

We need more information about your offset for the aftermarket rims.

This. We need to know the wheel width and offset before we can help you out, if it happens to be the same as stock (7", +45), then go with the 20mm front/25mm rear recommendation.

oops haha I thought he said he was on stock rims..my bad..either way all he needs to do is look at the wheelfitment thread I linked him to and do some basic math..