"Snug" Condom Recommendations?

My boyfriend and I ALWAYS use condoms, however, the ones we have tried (Trojan) always seem to slip off. He's not small, honestly pretty average, so I don't understand why this would be an issue other than the fact they are just a little too big. Any of you have snug condom recommendations (for someone who isn't less than 5 inches?)? Or have any condom use suggestions in general to prevent this from happening?