Quote Originally Posted by SCIfor55yrs. View Post
6" casters would lower you an inch if they work with the forks. However that will also lower the chassis .The Permobils already are pretty low. You will hang up a lot. I am in the process of getting an M300 with the 6" caster option. They have different forks that will keep the ground clearance the same as that of the 8" casters.
I spoke with Permobil and the forks are different

Quote Originally Posted by Tonyy View Post
Just an idea, Possibly check with your van shop, I know many van floors have plywood and you will notice recessed channels in the floor for the seats to lock into.
I have had my casters sit into the seat lock areas many times.

Could they make the floor lower where you drive to make things somewhat better.
My chair width is wider than the floor mounts. My left tires seat right on the channel pretty much but my rear tires sit past them by the sliding door. I still use my drivers seat also when others need to drive.