If you rely on a spotter to get the dumbbell into place you are going to struggle. As tenpercent said just kick them into place. The issue with dumbbells is that you have to stabilise them and this is why they are harder than barbells.
g8r80, if you can hit 225 on the bench then you can .
Well, if that 64yo dude can do 115's without a spotter, then I'll man up and continue to do what I've been doing - holding them on my legs, leaning back and popping them into place.