ditto on the lug nuts.... never use an impact wrench to tighten the lug nuts, use a torque wrench when possible....

A 3/4 inch torque wrench is ideal but a bit pricey, a 1/2 one will work but use a deep well socket and avoid using a long extension (or an extension at all if possible) as it can cause the torque value to be off due to the twist or give of the extension itself....(this applies more to torque specs that have to be really accurate, lug nuts not so much but good FYI info to know)

Harbor fright has there 1/2 clicker torque wrenches on sale from time to time cheap, your owners manual should have the listing for the lug nut torque spec....

 

Your mention of the extension altering the reading reminds me that a lot of shops use those "quill" extensions that actually do limit the torque applied to the lug nut due to each different one being rated at a different torque. But I still prefer a good torque wrench. Would be just a little leary of a cheap one unless it was checked to a standard. Usually get what you pay for. A lesson I've learned time and again.