Fixing to display base

twist ties through holes in base and over axle. alternately craft wire or rubber bands work well.

loop the bands over the tires and feed through the base, then back up and around the other tire.

Depending on the model, I usually use hevy duty black thread f the model has metal axles.  Otherwise, I've seen modelers use everything from 5-minute exopy to CA(super glue) to wire, to even screws.  I used a nut & bolt on one model, but that was a Sherman tank and I had access to the interior.

Peg the tires to the base with metal rod, add a drop of something like PL Premium adhesive in the holes and it will never move again.  This is for wood bases.

If you're using those clear display cases they normally come with some wire to tie the model down with,