Wifey scored an early Christmas present (for me). Lowes 1/2" Kobalt 24v Impact Wrench rated 650 ft/lbs with 4 amp batt. for $139. If this thing can break loose an axle nut torqued to 400 ft/lbs, I will be impressed. Probably not.
Are there any good online reviews for this Impact? It may be ok for what you need.
I'm heavily invested in Dewalt 20v line and I have the 1/4 inch impact (both single speed and 3 speed) and the 1/2 gun. That 1/2 inch is my go to tool for Tire changes. Regardless of the brand, IMO most of these battery impacts are very good these days for light duty work.