My 1530 came with the standard solid rubber tires and I'm curious if it is possible to change over to air-type tires. I ask this question because when I look at the clearance between my solid tires and the 1530's frame members it looks like there is not sufficient clearance for the wider air-type tires. Also, I have not been able to find any wheels for air tires that are compatable with my 1530. Any insight from the membership on this topic would be most welcome.