New toilets rocking! 3" plastic pipe?

Putting in a new toilet for a friend. Bought a new wax seal with plastic flange. Installed as have done before with other toilets but this toilet rocked pretty good. Removed the toilet, scrapped off rind and put toilet in place w/o ring and no rocking. Now here's what I think is my problem. The plastic sewer pipe is 3" in diameter. Could it be that the plastic flange is not fitting into the 3" pipe far enough and not letting the toilet frest fully on the floor? If this is what is going on, what should I use. Just a wax seal w/o a flange? Thanks for the help

That is exactly what the problem is. The wax rings with the plastic horns are a worthless piece of junk that should be banned from the face of the earth. Even if they don't cause a problem such as you are having, they perform no useful purpose. Some marketing genius figured out they could make a little more money for DIY suckers who would think that that funnel would somehow be better than just the Plain Jane Wax Ring and they could sell it for more money. These are a bigger problem in 3" drains than 4", but they are just crap!

Can Terry put in BRIGHT, flashing, neon colors at the top of every forum here:

ONLY USE WAX RINGS, JUNK RINGS WITH PLASTIC INSERT. PERIOD.

Ok, there, I'm done ranting.

flange

IF you think you need the plastic funnel, which you do not, then you have to get a wax ring labled, "For 3" and 4" drains".