Why is the ortho isomer a major product in the nitration of toluene?
A methyl-group is not t-butyl, so it isn't all that crowded.
There are two ortho-positions. 
There is also the possibility of an ipso-attack with the nitronium donor attacking the position of the methyl group, then shifting to the ortho-position. 


Given all that without any orientation effect, the ratio between ortho and para should be around 3/1 - 2/1. It is commonly observed around 3/2, so the crowding does have an effect.