Mastiff Dog Collar Help!?

my dog is named charly brown. he is st.Bernard and boxer.he is tall and long like a bernard and barrel chested like a boxer.most of his 125lbs is in his head neck and chest.i had the same problem.go to a feed store that caters to farmers.get a collar for a calf (you know a little cow or bull) chuck wears a 30" and the biggest i could find for a dog was 26"so i had to go to cattle collar's.they are identical but bigger so no-one will ever know unless you tell them.p.s. i only paid about 15.00