[chrisguyw]

Thank you, chrisguyw.

• Mask off wheels, leaving just the hub gap exposed.  Then apply expanding Polyurethane Foam Sealant from an aerosol can as sold for stopping drafts around window and door frames - eg:  Red Devil 0912 Foam & Fill.  Let set, then trim.
  
  
  

Polyurethane foam sealant is much "harder" than foam and will not compress/rebound to the same degree, and will limit the advantages of using foam to create a tire with more compression...........while the polyurethane will fill the gap, so will epoxy, tape, etc.  or just buy traditional wheels.....just depends on the degree of performance you are after.

Cheers
Chris Walker