I've got my slicks today m/t 20-8-14 and i want to mount on some
steel rims(6-14). But when they got the slicks on the rims they
could not get them filled with air. What's wrong?

 

slicks are a bitch to get the bead seated properly. make sure the bead is seating.

 

I'm from holland so my englis isn't so good. whats the bead?

 

Slicks are a bitch to bead, what kind of lube are you using?, i use windex so when its beaded the windex dries and the rim is less likley to slip on the tire, also is the core out of the valve stem?

 

the bead is the outer part of the sidewall that will go up against the lip of the wheel!

with slicks they will need to use an extra amount of lubricant/soapy water! Just be careful not to over inflate the tires when seating the bead to the wheel!

Anthony