The loaded tires are great when you are for instance mowing on a slope with a rear rotary cutter on the back to help the stability, BUT they are no way enough to prevent the raising of the rear when using a loader. You need a ballast box or a heavy implement on the back to offset the weight on the front end loader, not just to keep your rears on the ground, but to also ease the strain on the front axle/seals you are overstressing by lifting the rears and putting all of that load on the front. If you would like to search here there are thousands of post's about ballast boxes. You can easily build one or buy. Or have a heavy implement like a heavy duty box blade on the rear. You may need to load it with some concrete blocks though.depending how much it weighs. You MUST have ballast, a tractor as it comes off the trailer with a Front End Loader installed, is next to worthless for lifting. In fact it is downright scarey. I have 750lbs on my little L3400HST plus the loaded tires. That is about right for mine, Your tractor is larger, and has a much more powerful loader, so More than that is going to be needed.
James K0UA