Minimum fender/tire clearance for semi-offroad trailer (1 Viewer)

[Heckraiser]

Hi Folks,

I am a complete and total trailer newbie. Just kicking around some ideas for my daydream project, a semi-offroad teardrop style camper. This is all hypothetical, by the way, as I don't have space to build or store anything at the moment.

The trailer would need to be semi-off road capable. I'm not going to drag it up any severe trails, but the roads to some of my favorite campsites are just a little beyond "subaru-able." So figure the type of trail that a bone stock truck-based SUV (Xterra or 4runner) wouldn't really break a sweat, but something like a Rav4 would probably sustain rocker damage or get stuck, just to paint the picture.

So one thought I came up with is running a smaller tire (I'm thinking 235/75r15) and a flat trailer deck completely above the tires to maximize floor space and keep the overall width of the trailer down... similar to the types of trailers used to haul snow machines. A 235 tire is 29" tall, so the deck would have to be pretty close to the tires in order for it not to be a huge step into the teardrop (would also like the whole thing to be under 7' to fit into a standard garage).

So my question is: how much space should be necessary between the tire and the trailer to allow for tire uptravel?

Conversely, do you think I could run a smaller tire than 235's for the above-mentioned usage? 215's (27.7") and 205's (27.1") seem to be a common enough size. I should have plenty of ground clearance and the bottom and edges of the trailer will be built with "bump and rub" in mind, but I'm more concerned about the tire rolling over obstacles without getting hung up.

I'd love to hear your input! Thanks

 

[greentruck]

Sounds like a very top-heavy design. You want the center of gravity to be lower than the width of the trailer (when loaded) is a very rough rule of thumb. Might do some calculating on if that will be possible with your design. Consider than the basic military 1/4 ton trailer has been tested over decades against all kinds of unforgiving terrain and the wheels still sit outside and between the frame.

As for space between the tire and fender/trailer... it doesn't need to be much, but it needs to be there at the full upward compression allowed by the suspension. You don't want rubbing. And you need to leave a little clearance for tires getting caked with mud or for snow and ice clearance if you'll have it out in winter conditions.

 

[Heckraiser]

Thanks for the input I'll try and figure out where the weight would end up. The other alternative is to build wheel arches into the trailer body, but that would still have some impact on the floor space and add some complexity to the build (complexity tends to slow me down more than most ).

:edit: I wonder if a water tank or storage drawer below the floor level would improve weight distribution enough?

 

[greentruck]

It would help, but that would tend to go away as the tank is emptied.

On the 1/4 ton trailers, the bed is a pretty basic box, except it flares out at the top. The side fenders just bolt on and good aftermarket fenders are now available at reasonable cost. LFD2037 got a nice set that are illustrated here: My Trailer Build Plan W/Questions

 

[richxd87]

I think it really depends on your suspension, stiff leafs or some supple airbags/trailing arm setup. I built a trailer with a straight axle and 1500lb leafs and space btw the tire and the fender only compressed as weight was added to it. The axle doesn't really flex a lot as it was pulled across the terrain since its only attached at 3 points, so the entire trailer pivots on the axis of the tongue.

 

[Heckraiser]

It's going to be a straight axle with leaf springs, probably pulled from a junkard jeep/suzuki/yota pickup

 

[LAMBCRUSHER]

richxd87 nailed it...