Trailer to Track Same as 5th Gen - Dimension?

[pbcolt]

I'm building a camping trailer to tow behind my 5th gen. Does anyone know the hub face to hub face dimension of our rear axle?

Googling: "2014 4Runner Track Width" gives me a dimension of 63.2", but I think that is to center of tire.

I suppose you could also back into the correct dimension by figuring out what length axle would track ~63" with stock 17" wheels and 2.25" worth of wheel spacers that would work as well. Backspacing offset all sound Greek to me.

 

[DesertCanyons]

Trailer track width

Getting this right is a good idea. You want the trailer to hit the same ruts and high spots as the truck. Of course everything changes when you turn sharply at slow speed.
You should be able to measure this directly to within close enough for accuracy. Just measure out-to-out on the tires and then measure from the outside face of sidewall to the hub face. Use a yard stick or straight edge across the tire and find somewhere inside the rim through the spokes that matches the hub face. Multiply by 2 and subtract that from the out-to-out dimension.
Unless your trailer wheels have the same off-set as the truck it doesn't matter what the outside of hub face dimension is. Just get the out-to-out the same and the trailer will track behind the truck tires.
I built a trailer years ago to pull with my 1976 Toyota truck. I used tall narrow tires to decrease weight, spin speed and rotational inertia (the later may be a wash as diameter increases) and to get it to roll easier over obstacles, bumps and holes. Consider using taller tires.

 

[pbcolt]

I will pull a tape on it to see what I come up with to double-check. My first attempt says:

63.2" desired track width.
15mm offset from stock wheels = .59" or 1.18" total from both wheels.
1.25" spacers = 2.5" total from both wheels.

63.2" track width PLUS the offset (offset will make the center of wheel back/toward the inside) MINUS the spacer distance (spacers will push the wheels out 2.5" total) gets me:

63.2"+1.18"-2.5"=61.88". So I could order the axle at 61" and be .44" inside the track width of the 4Runner on either side.

Anyone see a problem?

 

[DesertCanyons]

Trailer track width

I think I follow your numbers. Not sure though. Are the spacers on the truck or the planned trailer?

Why add spacers to the trailer axle? Just order the axle to fit the desired width. Build your frame wide and place the leaf springs close to the axle hubs or wheels to reduce axle stress and keep the wheels vertical when the trailer bounces. When I built a trailer I bought hubs with the same lug pattern I had on the truck and pounded the hub pegs into a 2" square heavy tube. Welded slightly to keep it there. There is very little axle stress between leaf springs. It's nearly all between the leaf springs and the axle hub.

Check your trailer wheel offset first. Is it the same as the truck or different? What size tires are you planning to run? Remember, taller tires are better on a trailer and you don't have a lot of weight on a cargo trailer so smaller (narrower) tires may be fine. You also want the same lug nut pattern so you can use your truck spare on the trailer and vice versa.

The T4R tow rating is 4700 lbs but it's unlikely you will ever tow a load that weighs as much as the car. Estimate the weight of everything you'd put in a trailer and add the trailer weight. Divide by two and you have your tire load. Buy tires rated for that load or higher. The rating is for tires at full pressure. The capacity is lower if you de-air for sand.

If the trailer tire is taller than the truck tire then it could be used as a 2nd spare on the front of the truck and you drive in 2 wheel drive until you get to a tire dealer. I know someone who went through two tires very quickly on salt flats in Death Valley and was suddenly stranded in the desert. By pure luck and quick thinking they got help quickly and were out in a few hours.

 

[pbcolt]

Thank you!

I think I follow your numbers. Not sure though. Are the spacers on the truck or the planned trailer?

Why add spacers to the trailer axle? The spacers will just be on the trailer to make the new trailer axle hub-centric. The bolt pattern won't change.

Build your frame wide...

I'm using a former military M101A2 trailer so the frame dimensions are already set.

Check your trailer wheel offset first. Is it the same as the truck or different? What size tires are you planning to run? Remember, taller tires are better on a trailer and you don't have a lot of weight on a cargo trailer so smaller (narrower) tires may be fine. You also want the same lug nut pattern so you can use your truck spare on the trailer and vice versa.

Hopefully I can find 2 4runner Trail wheels so they match my truck exactly. If not, some SR5 wheels, or 17" Tacoma or FJ wheels - Whatever can be used on my 4Runner in a pinch.

The T4R tow rating is 4700 lbs but it's unlikely you will ever tow a load that weighs as much as the car. Estimate the weight of everything you'd put in a trailer and add the trailer weight. Divide by two and you have your tire load. Buy tires rated for that load or higher. The rating is for tires at full pressure. The capacity is lower if you de-air for sand.

I plan on buying 2 Load Range E tires for the trailer in 265/70/17 (same as my 4Runner). They might be a little overkill but the last thing I want is to leave the trailer in the middle of nowhere and have to come back to get it.

...

 

[DesertCanyons]

Military surplus trailer

Sounds like you have a plan. The build should be fun. Good luck.

What does the military trailer weigh? What was it originally designed and used for? If it's heavy then you'll pay for any savings in gas mileage, ease of driving, brake wear and tire wear, not to mention limited accessibility on rough roads due to the weight. If it's heavy consider selling it and buying a utility trailer with decent wheels or upgrade the axle (these are often sold with small tires). If it is currently unsellable, maybe finish the trailer to your liking and then sell it to a Wrangler or T4R owner.

Good luck and have fun, whatever you decide.

 

[pbcolt]

Sounds like you have a plan. The build should be fun. Good luck.

What does the military trailer weigh? What was it originally designed and used for? If it's heavy then you'll pay for any savings in gas mileage, ease of driving, brake wear and tire wear, not to mention limited accessibility on rough roads due to the weight. If it's heavy consider selling it and buying a utility trailer with decent wheels or upgrade the axle (these are often sold with small tires). If it is currently unsellable, maybe finish the trailer to your liking and then sell it to a Wrangler or T4R owner.

Good luck and have fun, whatever you decide.

Thanks, It will be a long process I'm sure.

The trailer weighs 1,300 lbs with the top, sides, and bows. From what I've read, changing out the axle and dropping the surge brakes can get you to ~1,000 lbs. Adding back a lid, RTT and camping gear I'll probably be at 1,400-1,500 lbs. Almost to the inch the trailer is exactly as wide as the 5th gen's without mirrors so you can see it perfectly when you tow.

For weight reference, an Adventure Trailers Horizon, a much smaller "Expo" trailer, has a base weight of 1100lbs. These military trailers really aren't as big as some folks think they are.

 

[DesertCanyons]

Thanks, It will be a long process I'm sure.

The trailer weighs 1,300 lbs with the top, sides, and bows. From what I've read, changing out the axle and dropping the surge brakes can get you to ~1,000 lbs. Adding back a lid, RTT and camping gear I'll probably be at 1,400-1,500 lbs. Almost to the inch the trailer is exactly as wide as the 5th gen's without mirrors so you can see it perfectly when you tow.

For weight reference, an Adventure Trailers Horizon, a much smaller "Expo" trailer, has a base weight of 1100lbs. These military trailers really aren't as big as some folks think they are.

Sounds great. I didn't realize the utility trailers weigh that much. For reference, a tent trailer that sleeps 4 weighs 2400 to 3200 pounds when loaded with water, propane, etc. I have my eye on a teardrop trailer to keep the wife happy when we go camping.

I built my trailer from steel tube, channel and angles, steel fenders. It had a 1" plywood floor, 2 foot high sides and a 4'x8' lockable lid. I built it around a 4x8 sheet of plywood so I could make a one piece lid to lock down and convert to a table when we stopped. It came out looking pretty nice and I towed it with an old 1976 Toyota truck with a 2.2 liter 4 cylinder DOHCC engine that I added headers to. I towed that down Baja a few times and out to Death Valley. I could carry dive gear and camping gear with it. Eventually I sold it to a guy with a Ford Bronco II (the smaller version) that had the same track width and same lug pattern.

 

[pbcolt]

Anyone else mind taking a look at my "equation" and seeing what they think?