Distance between tire & trailer?

[abosely]

On a leaf spring trailer, how much distance should there be between the inner sidewall of the tire & side of trailer?

Does it make much difference if the springs have a lot of flex & travel?

On a off road trailer. Wheeled fairly hard.

Cheers, Allen

 

[Coastline]

What part of the trailer? Frame, bed, side walls? Are the springs stiff? The springs on my trailers with 3500 pound axles are pretty stiff and really don't flex much at all and the axle behaves about the same as a torsion axle would.

My current custom build has 37" tires and I allow 2 inch clearance to the frame and a bit more to the bottom of the fender well, but this fit is limited by the format that the customer chose and, since he supplied the over sized tires and rims.

If your concern is the inner wall you will need enough space to tip the tire a bit to change it and enough room for mud and rocks to clear.

 

[abosely]

Ah, yes side wall of trailer. Plus with a flexy springs.
Is there a good rule of thumb for this?

 

[Heinz Modricky]

Technically, you just need to clear the body by millimeters on normal road conditions. Deflated tyres only broaden at the base.

But in off road conditions, you will experience the trailer slipping sideways into a rut. In severe circumstances, you will exceed the static load that is normally carried on both wheels, being exerted sideways on one wheel only. (This is due to the trailer falling into the hole and the deceleration of the trailer as it lands in the hole, adds G's to the static load, so a 3000lb load normally carried on two wheels can land up being 3500lbs or more, being exerted sideways on one wheel only.)

This will push the leafsprings sideways and depending on the tolerance and flex you have between all joined parts (shackles, poly bush, link plates) will determine the sideways movement of the axle.

Our build on the Metalian trailer has half an inch gap. Our shock is mounted vertically in the wheel arch between the wheel and the trailer body. We don't see tyre marks on the shocks from trailers that come in for repairs and servicing, so our experience is that half an inch will suffice.

 

[ntsqd]

Keep in mind that trailers do not articulate like 4x4's do over rough terrain. Very short term lateral displacements as discussed above and one-tire bumps are all that you need to consider.