What type of tyres? ..... Good ones. This is a demanding application.
Nothing to do with radials - just the fact that off-road and highway conditions have different, and in some ways, conflicting requirements. Bead cracking may be a pressure problem - the trucks may be using off-road (low) pressures for highway use.
Talk to one of the major manufacturers - there are suitable products and good advice on reaching a compromise solution.
John