Foam inserts for tyres?

[autonm]

Building up my first car for over 15 years... and ive got to the tyres.

Instructions for the B44 say front tyre + front insert + front wheel. So the front insert is foam.

But when im placing the foam insert into the front tyre is hanging out the side of the tyre as well. Am I meant to trim down the foam?? or just keep squashing it in there ? - just doesnt look right to me

thanks