gardenville - based on the piece I have here (.375" * .75" * 24 3/16") the weight works out to approximately 14.7 grams / cubic inch. A quick search, however, reveals a range of 15.4 - 16.4 grams / cubic inch.

There are alot of factors that come into play when selecting screw size and material thickness - terrain (full snow, partial snow), exposed logs or rocks, sled load, and above all, how much weight you're prepared to add and carry, if need be.

Here is a link to Flat Head screw sizes Flat Head Screw Sizes

As a suggestion I would use a #6 with 1/8" thickness but go up to 3/16" thickness for a #8.

Sorry to get so involved in YOUR project. I'm just so intrigued by it, I coundn't help myself.

Keep us posted about your obvious winner.