Fender Clearance Question

[Capebuild]

How much clearance space is suggested to leave between tire and inside surface of fender. For some reason 3 inches is in my head. Does this sound reasonable?

Also, in order for the fenders to fit "properly", leaving a somewhat equal radius from tire surface to inside of fender, I'd have to cut a couple of inches of the two sides
on the fender's bottom (to sort of position the fender so it's got a somewhat equal radius with the tire). Is this typical, to trim the fender sides? Just askin'.......

Thanks!

John

 

[MickinOz]

Not sure of the right answer John, but can tell you what I did.
Advice received from a trailer manufacturer was that lateral clearance is advised to be 50mm/two inches, minimum 1 1/2 inches.
That's the gap between the tyre and the wall.

My springs are rated to deflect 50mm with 600 Kg pushing down on them.
So, with much of the build complete, nearing final weight, I knew I had at least some of that deflection. At that point, I positioned my fender so that it looked like the circle of the tyre and the circle of the fender are concentric.
Worked out OK and about three inches of travel room remaining give or take a bit.

 

[Squigie]

I like generous clearances and am setting up the rough road TD for 1.5" sidewall and 2" of tread clearance, at full compression with Timbren suspension. But I have almost 3.5" of travel to consider, iirc. So that is more like 3-4" of clearance for mud, snow, and gravel at normal ride height. (Sidewall clearance is a bit of a compromise, brought on by tire choice and trying to keep overall width as narrow as reasonably possible.) If I was using a solid axle and leaf springs, I would have to allow more sidewall clearance for axle articulation.

But if you want a tight, clean look, and will be staying on paved roads and well maintained gravel lots, you can reduce the clearance to as little as 1/2" with some types of suspension (lateral and radial).
If you tighten things up, keep in mind spring deflection and the swing arm radius while doing the calculatin'. With torsion axles, leaf springs, trailing arms, etc., the axle/hubs are typically going to be arcing rearward as the suspension compresses.

It is all about what you're using, what you think you need clearance for, and how well the fenders fit the tires.

 

[Tony Latham]

I build the chassis with 4-1/2" of vertical clearance for a Dexter Torflex axle. When the cabin is added to the trailer, it settles of course.

Tony

 

[Capebuild]

Thanks Mick, Squigie and Tony for your thoughts. I probably should have mentioned I'm using a Dexter torsion axle.

I ordered a pair of fenders which, if I keep them concentric with the tires (which is what I'd like), will provide about 3 inches of clearance. I'll need to cut a bit off each side as
they would overhang the bottom of the cabin a bit otherwise.

thanks again.

John

 

[Squigie]

Seems reasonable.