That would mean that Earth rotates backwards.
____________________
It would also be roughly the same as earth reducing its tilt by about 10 degrees. A 'tilt' of 180 degrees would just mean that...
If the Earth were tipped 30 degrees from the ecliptic instead of the 23.5 degrees that it really is, the tropical zones would be a little larger, and the near-polar weather would probably be a little...
If the Earth tilted +/- 35 degrees instead of +/- 23.5 degrees, the winter and summer solstice would be stronger and would last longer assuming that the rate at which the Earth tilted stayed the same...