Tiger barbs are fine in a community tank so long as you have a group of them. They generally only start their fin nipping when they are bored and the group is too small.
Rams should be able to hold their own, even if the barbs start pestering them. They are able to defend themselves and in a planted tank there shouldn't be too much contact between the two groups of fish as the rams will stay in the bottom third and the barbs should stay quite high.
The only problems you may have is if the rams start breeding, then the barbs will find an angry cichlid if they come pestering. They can get quite territorial anyway, but if they breed, they will defend their territory aggresively.