3 ton puts you at 6k lbs. Not sure what rig your in or what the weight is. Keep in mind the distance the jack has to travel up to lift those tires off the ground. Smaller jacks don't lift high. I carry a 24 ton for my 5r that weighs about 4 tons. Always lift on the flat side of the frame next to the wheel. And, I generally need to put short 2X6's under the jack for that snug fit.
Don & Dona W/yorkies Gizmo, Master Chief, & Tali
2011 Flagstaff 8528 BHSS 2015 Ford 6.7 XLT
2010 Full Timers & Still Going