skizzo

In repairing a flat today (impaled on an exposed rebar stud in a parking lot, ugh), the OEM scissor jack just barely provided sufficient clearance before it maxed out its height. It was mounted under the frame where indicated in the manual. I didn't think it was going to get high enough until the last couple turns, and was surprised it was cutting it so close -- less than half an inch of working margin at full height. I talked with two other half-ton owners who both said theirs just barely cleared, too. Anybody else with a similar experience? Would you put a 2x6 either under or above the jack? Or is it expected to be that tight? I've never changed a tire before where I didn't have a couple inches of working clearance to the ground.