3,500 lb Pontoon Trailer Axle and Tire Setup to Stay Under 102 Inches and Launch in Shallow Water  

Question:

Expert Reply:

Hi Terry, yes you can build a 3,500 lb single axle trailer that keeps the pontoons between the tires and still stays under the 102 inch limit, you just need to be intentional with axle width and tire size so everything fits without rubbing or going over width.

A really solid starting point from what we carry is a traditional 3,500 lb idler axle like part # e65GR, which has an 89 inch hub face. That size tends to land right in the sweet spot for builds like yours because it gives you enough inside clearance for the tubes while still leaving room for tires and keeping your overall width in check. If shallow launching is a priority, I would strongly consider a drop axle version like part # e72GR since that lowers the frame a few inches and helps get the pontoons closer to the water without needing extra ramp depth.

For tires and wheels, staying on the narrower side is what keeps you legal and gives you that clearance you are after. Something in the ST175 range on a 13 inch wheel with a standard 5 on 4 and a half bolt pattern like part # AM31985 works really well with those axles. That combination keeps the outside width down while still giving you enough load capacity for a 3,500 lb setup.

Most manufacturers solve the shallow water problem the same way you are thinking through it. They lower the frame with drop axles, keep the tires narrow, and run the bunks between the tires so the tubes sit down inside the frame instead of on top of it. That is what really makes the difference when you are trying to launch in shallow areas without backing the trailer too far in.

I have heard of some boat trailer owners using silicone or a slick coating on the bunks which can definitely make launching easier in shallow water because it reduces friction, so the boat slides off with less effort. That’s why some people swear by it, especially when they can’t get the trailer very deep. The tradeoff is that it also makes the boat much easier to move when you don’t want it to, so you have to be extra mindful when unhooking or on steeper ramps since it can slide unexpectedly.

The one piece we would still want to confirm is your pontoon tube diameter and how far apart they sit center to center, because that will tell us exactly how much inside tire clearance you need to build around. That is what makes sure you do not end up too tight or accidentally pushing over the 102 inch limit once everything is assembled.

expert reply by: Heather A

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