Solution for Replacement Wheels and Tires on Pontoon Boat Trailer With Split Rims

Question:

I bought a 16 ft pontoon boat with a sissies trailor and they sed tires are shot and I need new tires but they told me tires are 680z9 and on split rims can you help me find what size tires I need before I drive 3hrs to pick it up it is 4 bolt pattern and single axle

asked by: Charles

Expert Reply:

Since those are split rims you would need tires with tubes for the wheels. Split rims have been discontinued since they are dangerous and prone to failure, so I recommend replacing the wheels as well. There is nothing that comes up for 680z9 tires, perhaps they are 6.90/6.00-9. I would double check the size. Either way it seems as though it has 9" wheels. I recommend moving to 10" wheels and tires if possible.

The Kenda 205/65-10 Bias Trailer Tire with 10" Galvanized Wheel # AM3H470 would be a good replacement option for this trailer. It matches the 4 on 4 bolt pattern and has a maximum load of 1,650 lbs at 90 psi. It also has a speed rating of N for 87 mph. I recommend contacting the trailer owner to make sure this will fit first.

This tire has an outer diameter of 20.4" and section width of 8.4". If they can measure the diameter and width of the existing tire, along with the current top and inside clearance, you can compare them. Typically you want 3" of clearance on top and 2" of clearance on the inside of the tire. If the 10" tire is smaller you have nothing to worry about. If it is larger, you will take half of the diameter/width difference and subtract that from the current clearance.

For a quick example, if the current tires have a 19.4" diameter the new tires would be 1" larger. This means you would lose 1/2" of clearance on top. If the clearance was 3" then you would subtract the 1/2" so that would take you down to 2-1/2". If you won't have enough clearance you're probably looking at 4.80/4.00-8 wheels and tires like the # AM30040. These have a significantly lower max load of 745 lbs at 90 psi so you would have to make sure it can handle the weight of the trailer and your boat.

expert reply by: Robin H