Narrow front wheels for Stagger Rib - 20mm wide?

[Hallsy]

I've read that you need to cut the inner edge of the std (25mm?) width front B4 wheels to be able to fit Stagger Rib tyres.

A friend of mine gave me some spare wheels he had from his B2, the rears are no good as offset is a lot lower, but the fronts look the same, just thinner, 20mm, as opposed to 25mm of the ones that came on my B4.

Does it sound like the Stagger Ribs would fit straight onto these wheels? How much is normally trimmed off of the std wheels?