Help With Foams

[MrSlow]

Hi there

I have bought some of those new 1/10 contact foams. I haven't used foams before and I am a little stuck on the next bit......

I have removed the inner ribs on the outer surface of the wheels (as advised) but I am struggling to get the tyre on without removing one of the outer edge rims too.
(Hope that makes sense)
Should I just be more patient, or is the outer rim removal the done thing?

Cheers

Lawrence