I agree that the hammer action of am impact wrench is what you need, however if you arent going to buy a shop-sized air compressor anytime soon- where is what my dad always did.

Have one guy stand/pull/exert maximum torque on the lug nut using whatever means you have necessary (lengthen your breaker bar), hold that under torque and....

Have the 2nd guy get as large a hammer as he can hold with one hand, and pound on the nut, wrench or the metal (wheel) directly adjacent to the lug nut - tap as hard and as rapid as he(or she...) can - this hammering sets up vibrations that, in the absence of a "real" impact wrench, might break your nut loose (when the tapping and torque are applied at the same time). The harder you tap, the more the vibrations might work for you.

worth a shot IMHO- it has worked for me before.

-John

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