Is there such thing as a 28 inch wheel?
Schwalbe is one of the few brands that lists tire sizes this way. Their 28's come in two ISO's. Tires listed as a decimal size such as 28x2.0 are a 622mm ISO, while tires with a fractional size such as 28 x 1-1/2 are a 635mm ISO.

635mm are an uncommon size to American markets but can be found on 


  "English, Dutch, Chinese, Indian Rod-brake roadsters"


from varying manufacturers and production dates.
From Sheldon Brown

622mm are commonly referred to as 29 and 700C sizes, which are commonly found on current production mountain and road bikes. 29 and 700C tires are interchangeable as long as the rim width can support the size of the chosen tire. For example a 700 x 50 tire roughly equates to a 29 x 2.00 , or in Schwalbe terms 28 x 2.00"

*Answer has been edited thanks to people paying more close attention to the question than I did.