These are for my atc. I have a pair of prior studded with screws duro holeshot nock offs there 20" tires. Is it worth putting new screws in them or is the chen shin 18" knobby a better choice. I ain't racing just looking to ride in the ice alittle. Im thinking 29" would 've better for more clearance. How long of screws should I use long ensue to go all the way thru or kust in the knob. Last whats goid screws. That will last.