I use a pair of flat 6' aluminum ramps rated at 2500 lb per axle. I recently tried them with my JD4310 with the loader and bush hog mounted. I estimate it to be pretty much max for them and it loaded with no issues.
One thing to look out for with arched ramps is ground clearance. I bought a pair of arched ramps from TS and tried to load my racecar with them and it bottomed out on the arch.
I also have a pair of 7' arched aluminum lawn mower ramps. I think they are rated at 750 lbs per ramp. I accidentally threw those in the truck when I went to pick up an old 8N that had a loader on front and an Otis elevator gear case on the back for
ballast. We ended up supporting them in the middle with concrete blocks and winched that sucker right up on the trailer without damaging the ramps.
Make sure you go over them good with a file and a pair of gloves on to clean the welding spatter. I recently tore a big gash in my hand on my aluminum ramps from a piece of welding spatter. Last time I handled them I felt another piece I missed so I need to go over them again.