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Upgrading Tire Size and Suspension on a Homemade Hovercraft Trailer


I have a hovercraft trailer that is home built - freshly beefed up by yours truly. There is, currently, a 2.5 diameter axle with 4.80 x8 tires on it with a 4 on 4 bolt pattern. I have 3 clearance from the inside of the frame and 2 clearance to the floor. From the tire I also have an ancient set of springs that are about 48 long and are SHOT. I am thinking of going to a 3500 lb set of springs and a 10 tire with a 6 rim. 1 Will the tire have enough clearance for the frame currently 3 2 I realize I will have to retrofit the springs to the axle. 3 What do you recommend for a spring kit and what do you recommend for a tire? The trailer has not been weighed yet, but, my guess is approx. 900lbs. The hovercraft only weighs about 750lbs.


Expert Reply:

The wheels that are currently on your tires are 3-3/4 inches wide, but the width of the actual tire (section width) will be greater. The section width of your 4.80/4.00-8 tires is 4.6 inches.

Moving up to a 6 inch wide, 10 inch diameter wheel like the Kenda 205/65-10 Tire and Wheel Combo 4 on 4 Bolt Pattern, # AM3H460, will have a section width of 8.07 inches. This will bring the tire approximately 1-3/4 inches closer to the trailer frame leaving a 1-3/4 inch gap. This will be plenty of room to add a wider tire.

Another factor that you will want to consider when moving to larger wheels and tires is the overall diameter of the new tires and the fender clearance. The 205/65-10 tires will sit approximately 2-1/4 inches closer to the fender than the 4.80/4.00-8 tires that you currently have. Be sure to measure between your tire and fender to ensure you have enough room.

I have attached a few FAQ articles on trailer tires for you to check out.

For the leaf spring kit, we will need to piece together some items that will be compatible with your axle and trailer. Your 2-1/2 inch diameter axle tube is not a common diameter for axles. Currently, we only carry one u-bolt, # 175668, and one u-bolt plate, # 117858, that is compatible with your 2-1/2 inch diameter axles. You will need a total of 4 u-bolts and two u-bolt plates.

The lowest capacity leaf springs we carry that are compatible with this u-bolt plate are the 4-Leaf Slipper Spring, # SP-230275. This leaf spring has a 2,000 lb weight capacity per spring and 2 springs will have a total capacity of 4,000 lbs per axle which will provide more that enough support for your trailer. The original hangers will need to be cut off since they probably will not accept a 2 inch wide leaf spring. I would recommend installing hanger kit # APS6SE. This hanger kit, along with the u-bolts and u-bolt plates, will provide you with all of the hardware that you will need to install these leaf springs on your trailer frame and axle.

Assuming your axle has already been properly positioned, make a mark on the trailer frame for the center of the axle and space the hangers 12-1/2 inches in front of and behind that mark. If you would like to check that your axle is properly positioned, check out the diagram that I have attached.

You could go with lower capacity leaf springs for 3,500 lb axles, but they will have a width of 1-3/4 inches and we do not offer any u-bolt kits that will work with a 2-1/2 inch diameter axle and a 1-3/4 inch wide leaf spring. If you want to pursue this options and come up with your own u-bolt kit, let me know and I can recommend a leaf spring kit for you.

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expert reply by:
John H

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