Can Adding Larger Tires to a Trailer Increase Its Capacity

Question:

I have just recently bought a 4X8 trailer from a person and drove away with trailer in tow on the tongue of my 4X4 Explorer. The size of the tires on the trailer are 4.80X8.00 and there is roughly a 20 degree angle when the trailer is hooked up. Im wondering if this is okay? Secondly, the trailer was purchased for my families move to Arkansas and have calculated our load to be around 1200 lbs. The load range on the tires is 590, which I believe I should get another set with a higher range. I want to get a overall larger tire to lessen the angle, and be able to stand the load. How big of a tire can I put on the rims for the trailer, and what rating should the tires be?

asked by: David

Expert Reply:

I am glad you asked these questions. First, to tow a trailer level you need only a ball mount with the proper rise or drop. I have included a link to our FAQ article that explains how to measure for rise/drop and a link to our ball mount main page.

For the tires, going to a higher capacity tire does not increase the capacity of the trailer itself. The trailer capacity is set by the axle capacity. There should be a plate or sticker on the trailer tongue or frame somewhere that lists the capacity. That is the limit that you can put on the trailer.

If you cannot find the axle capacity information on the tongue or frame then it may be on the axle itself. If it is not there then you will need to pull off a hub and get the inner and outer bearing numbers stamped into the metal of the bearings. With this information I can confidently identify the capacity of the axle.

After we know the axle capacity we can determine if there is a higher capacity tire in 4.80-8 or 4.80/4.00-8 tire that will work. I would need to know the bolt pattern of the wheel also. It will either be a 4 on 4 or a 5 on 4-1/2 bolt pattern. I have linked our FAQ article on how to measure bolt pattern for you.

And finally, going to a larger tire will also raise the center of gravity on the trailer some. This will increase the likelihood of trailer sway and can cause some traction problems.

expert reply by: Michael H

Paul

1/19/2020

so if increasing tire size does not increase trailer capacity why use bigger tires

Jason S.

1/20/2020

Sometimes using larger tires gives you a ground clearance at your axle that is preferable. Sometimes the coupling connection height is assisted by a slight height increase. Other times people want to change the style of wheel for aesthetic (appearance) reasons. Trailer capacity is determined by many different things from tires and wheels to suspension, frame, axle capacity, etc. and all the components working together with the limiting factor being the weakest component in the entire system.