I only go heavy on dumbbell curls every so often and when I do, I'll go up to 85's using a little momentum. Otherwise, I usually don't go past 60's and I focus more on pumping the blood into the muscle.
I used to love doing heavy barbell curls. I could get up to 185 for a good 8-10 reps, but now I have tendonitis in my right forearm which prevents me from gripping the bar well and even with wrist wraps, I won't put more than a 25 on each side now.