frontal area requirement?


New Member
hi, what does the law say about adhereing to frontal area requirements?......say my truck manual states 50 sq/ft max and the actual measurment of the trailer is 52.7 sq/ft--do i get hauled off to jail??? that like driving 53 mph in a 50 mph zone?.....does the angle of the area of the trailer front play a role in the computation( ie; the greater the slope the lower the sq/ft?....thanks larry


Senior Member
frontal area requirement?

As far as I know, there are no frontal area laws. The TRUCK MANUFACTURER is the one who specifies the limit. So if the truck is 'rated' for 50 sq ft and you tow 52.7 sq ft, the police won't care one bit. However, if your truck breaks down, the manufacturer may decline to perform warrenty service, and if you were to get into an accident, a really sleazy lawyer (as opposed to a normally sleazy lawyer :) ) may try to make a big deal about it.

I'm not sure, since I just recently heard about 'frontal area limitations', but I suspect the reason behind this is wind resistance. If you have a large frontal area, it will be harder to pull, putting more strain on the engine and transmission, as well as the hitch and mounting. Thus, it seems likely that only the vertical component of a slanted area would count.

Let us say there are 2 trailers, both 8 feet wide and 10 feet high, with the floor 2 feet above the ground. One is straight up and down, and the other has the top 4 feet slanting backwards. Figuring the frontal area of the first one is easy, 64 square feet. I think the second one would also be 64 square feet, despite having more surface area (slanted area would be 5 feet high rather than 4 feet high (hypotenuse is square root of sum of the squares of the sides).


Senior Member
frontal area requirement?

John is correct. The frontal area limits are put on by the manufacturer. The legal area or "law" does not enter into it. Wind resistance is the reason for the recommended limits.
Many folks have purchased travel trailers based on their vehicles "tow rating" and are very disappointed at the performance when they finally get around to actually towing. Part of the reason is the wind resistance due to the frontal area of the trailer. I gave some examples in my other post here.

I'm not sure how the slanted front would fit into figuring the square feet - but I do know that a streamlined shape will tow easier than a block shape. I like to think of it as how big a hole do you need to punch into the wind. :)