jdnet, you have a valid "stupid" question. Based on the weight of the item described and the amount of overhang on your tailgate, only about 20% (160lbs) will be distributed on your tailgate. Even a Chevy can withstand that amount of weight...I think.

Your biggest issue is the type of material you are transporting. k.b. hit the nail on the head when it comes to transporting granite or other material of this type.

I have been transporting antique furniture for over 30 years. Included has been furniture that have tops of various thickness made of marble, granite, soapstone, glass, etc. IN ALL CASES this type of material is always transported, wrapped and in the vertical position. It all has to do with lateral strength, or lack thereof. This is why you always see this type of material transported by professionals in the upright position.

I can appreciate the others that have suggested various ways to pad the load but none of that will overcome the physics associated the stress exerted on the item in the horizontal position. You may very well get by with the transport as planned...sometimes we are lucky or just get by with it. FWIW, I would build an A-frame and do it the way the professionals do or just have it shipped or you can just try your luck...your call.

 

While composing my post you posted your successful transport. Glad it worked out. I was just trying to convey my knowledge and experience. Good luck on the next piece and enjoy your purchase.

 

My thoughts exactly.