Ok, to answer your questions: 37 X 12.5 in spare on 8.5 in AEV Katla rim Arm extends out 39 1/2 in full open Arm to tailgate clearance (arm closed obviously) 7 in Top of tire to top of tailgate (arm closed) 4 1/2 in. remember the mount tilts in at the top so the tire doesn`t fall off while mounting *Keep in mind, I have a Gear America recovery shackle hitch installed in the receiver which extends out about 4 or 5 in, when the arm swings out it does not hit/rub the shackle at all, there`s about 3/4 in clearance and the tire itself sits even higher... Unless you have a trailer spare tire mount on the very end of the trailer tongue, I don`t think you would have any clearance issues, especially considering these trucks sit high stock and usually require a "drop-hitch" to keep the tongue height correct. If you`re still unclear on clearances and "real world" tow ratings give the manuf a call, they`re very helpful. Pics on the website are also very helpful...see previous posts for contact info.