Advice on Axle Size for trailer build.

[SubmarineVeteran]

Hello all. I’m new here and working on my first trailer. I have a used trailer that I’m going to use as my build to start from. I’m currently gathering all parts needed then having someone weld it up to my specifications. The trailer was a camper trailer at one point and is an odd sized width. The width of the trailer is 43 1/4 inches. Currently it has 205/75/R14 tires on it. Tires seem to measure around 8 inches wide. I believe the Axle is a 2000 lb axle as it is 1 1/2 inches square. Currently it measures 54 inches from Hub to Hub with the closest measure I could get. Spring Center to Spring Center is 40 inches. Spring length looks like a standard 26 1/4 inch length. Currently between the tires and the frame there is only about 3/4 of an inch. So, I’m looking at purchasing a new axle and hubs. Possibly adding brakes. I’m also going to use 15 inch Jeep rims with 31/10.5/R15 tires since that is what I will be upgrading to on my Jeep Wrangler. I will be upgrading to a 3500 lb axle. So, I’m thinking I need a 61 inch or 63 inch axle with a 40 inch spring set spacing. Does this sound right? Would you go any wider? It will be a custom sized axle due to the spring spacing and want to ensure I order correctly. Does anyone have any thoughts? This is my first time building something like this and hate to order a large custom part incorrectly. Attached are some photos of the trailer. Thanks in advance for any advice.

 

[mikeprince]

Axle orders roughly need three things:
- weight rating; 2k, 3500 lb, 6000 lb, etc
- hub face measurement. The distance from the wheel mating surface at one wheel (where the wheel touches the axle hub) to the other wheel
- spring center measurement

Yep, there’s more but this gets us started.

For axle weight rating you get two things: bigger axles mean bigger bearings which is good for durability but (marginally) bad for mileage. It also affects your hub selection (you won’t find a Toyota 6x5.5 hub on a 2k axle).

Finally spring center is simply the distance between your spring centers


It’s all a balance. Nothing hardcore? Put a 3500 lb axle on a trailer rated for 3k. Long washboard roads with a heavy 2500lb trailer? 6k axle (like the m101a1)

For the hub face, measure the widest point in the wheel well that your tire might interfere with, then add twice your wheel offset, then add your tire width, and add another 1 inch to give 1/2 inch clearance on each side.

 

[SubmarineVeteran]

Axle orders roughly need three things:
- weight rating; 2k, 3500 lb, 6000 lb, etc
- hub face measurement. The distance from the wheel mating surface at one wheel (where the wheel touches the axle hub) to the other wheel
- spring center measurement

Yep, there’s more but this gets us started.

For axle weight rating you get two things: bigger axles mean bigger bearings which is good for durability but (marginally) bad for mileage. It also affects your hub selection (you won’t find a Toyota 6x5.5 hub on a 2k axle).

Finally spring center is simply the distance between your spring centers


It’s all a balance. Nothing hardcore? Put a 3500 lb axle on a trailer rated for 3k. Long washboard roads with a heavy 2500lb trailer? 6k axle (like the m101a1)

For the hub face, measure the widest point in the wheel well that your tire might interfere with, then add twice your wheel offset, then add your tire width, and add another 1 inch to give 1/2 inch clearance on each side.

Thanks! I’m understanding all of that but not quite 100% sure if my measurements are spot on, on the length I’m trying to decide on. Just don’t want it to be way to wide or to narrow. So... about 1/2 inch from the frame is what you’re saying is ok? Just seems so close to me. But, then again I’m new and that’s why I’m ask. Thanks.