please see :
http://www.tundrasolutions.com/forum...n-2007-tundra/
they will fit fine... unless you move to a 20 inch rim and a much more expensive tire a 33x 12.50 20... which looks awesome in a mud Terrain...but $300+ a tire.....
see the posting above... a guy has 18's with 33'4 on... not sure what that is...
personally...look at the 33's...some samples that look awesome
Another question for you... are you towing or 4x4 in off road, or dirt.
With all these a stronger rim the better, and more tire the better!!!
I tow, but might try to manage with the 20's...any bigger... its a street vehicle only!!!
goodluck