Concrete is not good for tires over time. I cut up a stall mat for the tires to rest on and for the jacks. The weight makes them act as if solid. Don't get wet, and work well.
Elliott & Vicky, and Sadie the GSD copilot
2014 36RE, Onan, Titan disc brakes, 17.5 inch Sailun H tires, lots of other options
2013 RAM 3500 CC, LB, DRW, Cummins, AISIN, 4x4