If the 100,000 mile warranty you're referring to is the Hyundai factory warranty, you're in for a shock: that warranty only applies to the first owner.
As far as wheel shimmy goes, this is an issue with Elantras and it may need to be balanced on a Hunter machine. You can see what Hyundai tells their dealers about wheel shimmy
here. Click on "NVH", then ''Wheel & Tire". They know it's a problem and tell their dealers how to fix it.