A question for you trailer building guys on here. I am re-habing an old tandem pull type RV into a tandem utility trailer and have a fender sizing question. My axles are on 36" centers running 15" 225 series tires. How or what guidelines do I use to measure up for teardrop fenders? I know that I need 10" wide fenders, but the common sizes for length are 68" or 72". Of course where I'm at they have to be ordered in so I can't mock one of each up. Don't want my fender gaps to look like ***. Suggestions?
You didn't mention the profile of the tyres so I am going to assume 70series.
That has a diameter of 27" [ 13-1/2" Radius ]
So the measurement is Radius + Wheelbase + Radius [ 13.5+36+13.5=63"]
63" from front edge to trailing edge of the tyres , so if you allowed 2-1/2 to 3" clearance = 68" to 69" Fenders
You can lay the fenders upside down on the floor and stand in them and give it a slight bend outwards if you prefer 69" Fenders
I do this often because when I import them they are stacked inside each other and the measurements change
Measure the gap between the Axle and frame, and this is how much above the tyres the fenders need to be, so if the suspension bottoms out it doesn't wipe-out the fenders.
If you want the fenders lower, add suspension stoppers to the axle or frame.
Don't use large fenders on small wheels or short wheelbase or they will look like eyebrows
see photo of a 66" fender with 25-1/2" tyres and 34" Wheelbase
