I have ramps I made from some peices of metal flooring that is used on the upper floors of metal buildings,also as fire escape stairs--it looks a lot like the aluminum ramps you can buy ,but are made from 16 ga.galvanized steel instead-they are about 8" wide and very sturdy,and do not weigh a ton either...they have punched holes and slotted areas on the top surface for traction,and the edges have a "U" shape so they resist bending quite well..
I was lucky to find several 8' sections in the metal pile at the local dump, when they renovated the highway department garage and had leftover peices from the new fire escape they had to make to bring it up to code,and they had just tossed them out!.(our tax dollars at work,eh?)..
I cut slots in the sides of them about 2' from one end and bent them into an arch shape, and used angle iron to bridge that area and welded the slots shut to strengthen them,then bolted some 1-1/2" angle iron to one end, that fits in the space between the trucks bed and tailgate to prevent them from being yanked out by a spinning wheel when you drive up on them..
(nothing sucks more than having the ramp on one side get chucked out when your 3/4 of the way up the ramp,and a 600+ lb tractor and YOU go crashing to the ground!--I busted a transaxle right in two once when that happened,and my leg darn near got busted in the process! )..I hate driving OR backing a tractor up ramps into a truck bed,even if the ramps are long and the angle isn't too steep..letting one creep up in low gear,while you stand beside it and try to steer it,is dangerous too,it can slide off and crush you in a heartbeat..
The ramps work well,the arch makes it easier to drive up without having the deck botom out on them,and get hung up---but I find it a pain to carry them in the truck bed,being a inch or so longer than my stepside bed is,and they wont lie flat as a result--the bed is already very limited for space,I have a tool box that "robs" 2' ,leaving only about 6' of length..I need to leave the tailgate open and chain it level ,to let the rear wheels sit on it..not my prefered method ,I'd much rather be able to close the tail gate..
(my MTD tractor wont even FIT in my truck bed,the deck is too wide,my bed is only 50" wide,and my 46" deck chute sticks out too far--that forces me to drive it way up onto the side rails on the top of the bed, and use plywood to brigde across the bed,if I want to transort it with the deck on it!--makes it topheavy and unstable,and it sucks!)...
So I only use the ramps when I have too--I have a retaining wall made of 2x4' concrete blocks I can back right up too and drive the tractor right in along side of my driveway,so I do that most of the time--but I often need the ramps to UNLOAD the tractor when I get where I'm taking it too,if the place has no hill or similar wall to use in tha fashion....
The setup I liked best was on my old GMC,I had a homebuilt flat bed 6'6" wide and 8'3" long that had no wheel wells,and a electric winch powered crane setup I made to lift heavy items..I used a nylon "tree saver" winch strap sling with two "eyes" wrapped around the tractor,and I'd lift it straight up, and swing it into the bed easy as pie with the crane..and I could load two tractors side by side,plenty of room--I often put 3 or 4 at a time in it when I used to fix them for customers..I've contemplated putting that bed/crane on my current truck,but its in need of much "restoring",it's gotten very rusty, and will probably need new plywood decking..its 12 years old and has been sitting out in the weather..
It was much safer than driving,pushing,or winching a tractor up the ramps ,and was priceless when you were offered a "dead" tractor sitting in the weeds in someone's back yard or woods,with 4 flats,or frozen to the ground !..I got many "freebie" tractors that way, because most other folks who wanted them didn't feel up to the task of geting them into their truck manually...