35x 12.5 x 18 , will definitely be a shorter tire, most measuring at or under 34,5" whereas the stock Tremor tire measures at 35.1."
go to tirerack.com, find the tire brand and model you want and click on "Specs" , it will give the measurements of every available size. height width , tread width, etc etc.
........................... height .....................section width....................tread width
295/65-20.......... 35.1"............................... 11.8.......................................9.8
35x12.5 -18........34.5.............................. 12.5.....................................10.5
285/75-18..........35.1" ...............................11.2........................................9.0"