the tire rack guy is recommending that if i go with 255 tread width, i should get the 40 series tire

really? i never heard that. he said the 45 series at 255 would be too tall.
i know its a tad taller, but i thought it was negligible. we have plenty of forum members that go with the 255 45R 20's.
i am going to get sport springs, so maybe i should get the 40 series???
thoughts?