When I replaced mine I bought the longest ones I could get at a Walmart. I don't think they make 30 inches, but I'll be down at the coach tomorrow and if I remember I'll measure them.
Point is that they clear plenty of windshield to see out of and the don't have the same tendency to lift off at higher speeds or in strong winds, which the long ones did.
2006 Patriot Thunder C13 Allison 4000
2010 Ford Flex Ecoboost AWD