Tyre to Guard Clearance Question

[Out-Station]

Hi all. Been looking at a few tyre options for the boat trailer. 3500kg BMT package on 8 leaf load share spring setup. What clearance tyre to guard do you recon i would get away with? Thinking 50mm??
Scott

[CT]

Is this one going up the beach Scott?

My trailer on the old rig and the one on the new rig both had clearance equal to the clearance from the top of the axle to the chassis. No idea how much of it I ever used but I did make the mistake of looking in the side mirror as I charged across a soft patch just short of the Orchid shop. I shit myself when I realised the whole wheel was well off the ground! Not sure if the take away message is allow plenty of clearance or, don't get a rush of blood to the head and just drive slower, or just don't look in the mirror when it all goes to crap and you lean on the loud pedal!

Cheers
Craig

[Out-Station]

Yep Craig, the old rig had healthy black skid-marks on the underside of the guard, i guess that one was to close!!. The new one, well all clear so far, just got to find the sweet spot!! Love those fraser woopy-doo's redlining in 2nd hoping like hell the whole shooting match doesn't break in half!

[tunaticer]

I work on 15mm more than the distance from the axle to the trailer frame or rubber bump stop if you have one.

[Out-Station]

Jack, thanks, not sure im following you. Currently i've got about 60mm clear between top of tyre and underside of guard. With a bigger tyre and lifting the guards up closer to the boat as far as i can i figure i might be back down around 45mm top of tyre to underside of guard. Was thinking this might be a bit to close?

[CT]

Jack, thanks, not sure im following you.

He's using the same theory I did. The maximum axle travel until it hits the chassis or bumpstop, then in Jack's case he's added 15 mm extra clearance. That way the axle will bottom out before the tyre on the guard.

Whether you need that much or not is the part I couldn't answer,

[tunaticer]

It needs to be higher than the maximum travel of the axle because it is usually one spring bottoming out and the other almost suspended. When the happens the pivot point is where the axle bottoms on the chassis = the wheel height is more than the travel at the springs.

If you only have 30mm of travel between the axle and chassis / bump stop then 45mm is fine.....very unlikely you have that small an amount of travel. Best case scenario is you will wear a hole through the guard with the tyre, intermediate is you destroy the guard, worst case you punch the guard through your hull.