How to Choose the Best Tires, Wheels and Axle for a Homemade Jet Ski Trailer

Question:

building a trailer for 2 jet skis. i have 2 rims and 4.80 tires but wondering if i needed to go with a bigger tire. will be pulling it on the highway. and also what size axle do you recommend? the one i have is a 1 1/2 square tube with 5 lug spindles.

asked by: Paul T

Expert Reply:

Finding the ideal tires, wheels and axles for your trailer will depend heavily on the overall weight of the trailer. For example, a jet-ski can weigh as little as 400-500 lbs on the light end and around 1,000 lbs on the heavy end. You must also consider the weight of the trailer itself sitting on the axles. Also, keep in mind that if the axle is positioned properly, the tongue of the trailer should hold about 10 percent of the total weight.

For example, let's assume that your jet-skis weigh 1,500 lbs combined (750 lbs each) and the trailer weighs another 500 lbs, that puts you at roughly 2,000 lbs total. You can probably get by with a 2,000 lb axle like part # 20545I-EZ-72-15, but your 4.80-12 tires will only give you a maximum load capacity of about 1,800 lbs. If the tongue supports 10 percent of the trailer weight, then with this combination will be pretty much maxed out as far as weight is concerned. If your jet-skis or trailer frame weigh more than this example, then you will need to step up the tire size and axle size.

The next size axle is a 3,500 lb axles like part # 35545I-EZ-89. You can stick with the 12 inch wheel, but you will want to change to a ST145/R12 tire like the Kenda Karrier S-Trail # AM10140, or the aluminum wheel and tire combo, # AM31215. An aluminum wheel would be best for your jet-ski trailer because it will hold up to rust and corrosion much better than a steel wheel. These tires have a weight capacity of 1.520 lbs each. They are also radial tires which are much better for highway and pavement driving. They dissipate heat much better and have better traction compare the 4.80-12 bias ply tires.

I'm not sure what size axle you have, but if it came with the 4.80-12 tires and wheels, it is likely a 2,000 lb axle. Some axles have an identification tag on them that lists the capacity. Otherwise, if you would like to send me some spindle measurements for the bearing and seal seats (see picture), I'd be happy to look it up for you.

A few other parts you may also want to pick up are leaf springs, a suspension hanger kit and a u-bolt kit. I've linked a few options below for each axle capacity.

2,000 lbs Axle:
Single Axle Hanger Kit # APS4
U-Bolt Kit # CE23000
Leaf Spring # SP-113275

3,500 lbs Axle:
Single Axle Hanger Kit # APS4
U-Bolt Kit # CE23002
Leaf Spring # e54SR