Lady Dominatrux
Dominatrix of Baseball
Factory tint on rear windows is generally pretty close to 20%. If you want your fronts to match, go pretty close to that. If you go 35%, it will still look pretty decent. Different brands of tint also have slightly different shading (brownish/grey/black), so you may want to take a sample out to compare against your factory tint.
Good tip. My rear windows are definitely darker than my front windows in fact I do not think my front windows have tint at all. The sun is always blinding me even with sunglasses on and the visor blocking it.
Thanks!