Small Utility trailer 8" to 15" tire upgrade is ok to do?

mansters

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Feb 25, 2013
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I bought this trailer on CL for dirt cheap, for my inflatable,
At fist glance i believe it was one of those harbor freight trailers, but its not its another brand, it weights about 150lb
It has those small 8" tires, 5 lug, it has 1" spindle shaft, It needs tires, and i want to upgrade the size of the wheels. money is short so Im curious if its safe to install some 15" rims, I have a new set tires and rims that i been storing in my garage for some time now, there galvanized,
Is this possible or a recipe for an accident


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H20Rat

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

yes, it will work, if you get rid of the fenders. (which is also illegal if you run it on a public road)
 

ondarvr

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

And if by chance the bolt pattern is the same...not likely though.
 

Jonnybbad

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

At a bare minimum you'll be needing new hubs that will mate with the rim's bolt pattern and new fenders. This would appear to be a "savings faux pas" situation. 8 inch trailer tires are also immensely cheaper than 15 inchers.
 

IraRat

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

I'm sure the bolt pattern is different, but you have another problem:

How wide is your inflatable? My guess is that bed is either 40" or 48" wide, so unless you rig something to hold your boat on its side, it may hit the tires.

And you may be able to find hubs to fit your 15" tires, but those hubs might not fit the spindles on your axle.

And if you're axle was made of c-channel instead of spindle, you could easily widen it to avoid hitting the tires.

Amazing how a stupid little trailer can be so complicated.
 

mansters

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

I already strip the trailer down to the bare frame, reinforced it by welding it more I extended the tongue out, the bolt pattern is the standard 5 on 4.5, the bearings are in good shape
I'm removing the fenders as i plan to run Boards over the tires where the boat will be sitting on, By the way the boat weights about 150lb assemble plus tackle and beer lol, i dont plan to carry the outboard on the transom during tow, its going inside my car with me. I plan to getting to the launch ramp and sliding the boat down as i fabricated some launch wheels,
 

lrak

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

Its possible, but it makes no sense. Why don't you want 8" tires?
 

mansters

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

Its possible, but it makes no sense. Why don't you want 8" tires?

I already have a brand new set of 15" tires laying around
Not to mention all the bad feedback I read about those tiny 8" tires
 

cannonman

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

I also have a utility trailer with 8" tires, so I know that feeling of wishing they were bigger. I tell myself that there are tons of trailers out there with 8" tires and they seem to do alright. I stay below 65 mph. I haul an ATV about 3 hours each way for hunting and no problems so far. Good Luck!
 

lrak

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

Don't believe everything you read. ;) IMO, you are asking for trouble to solve a problem that doesn't exist. The risk of a 12 or 15" tire rubbing the fender is greater than the likelyhood of problems from a properly inflated newish 8" tire.
 

Silvertip

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

For the load you carrying the eight-inch wheels and tires are perfectly adequate. They've been used on boat trailers and utility trailers for decades and the only issues are under inflation and overloading which, by the way, are the same problems people have with bigger trailers.
 

Bronlonius

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

I have a very similar trailer, that has 15" car tires on it. There are a few issues you'll have to deal with:

1. The axle probably isn't wide enough for the offset that most 15" rims use. Mine has a wider axle so that it uses the same size rim/tire of the car I used to tow it with.

2. The bigger tires will bounce more, so you need to air them down if you pull the trailer empty or with a light load. Otherwise it will scare the #%^ out of anyone behind you.

3. Most 15" rims use 5 lugs, and there are multiple bolt circle sizes for 5 bolt. I have 5 on 4.5 hubs on my trailer, which I bought at northern tool. Not sure how easy it is to find 5 on 4.25 or 5 on 5 hubs for a 1" axle, I lucked out that my car had the same bolt pattern, but depending on what kind of tires/rims you have laying around, you may not be as lucky.

I towed my little trailer on a 2000 mile interstate trip and it held up great with the bigger tires, the advantage is the wheels don't turn as fast so the bearings don't overheat. After driving 300 miles at 70mph, I could still touch the hubs without burning my hands.
 

mansters

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

its not only going to be used for a boat trailer, I have a lifted ford f350 with 38" all terrains and it has a camper shell, so this trailer will also carry my ATV,
 

NYBo

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

If they fit, I don't see a down side.
 

lrak

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

After driving 300 miles at 70mph, I could still touch the hubs without burning my hands.

If your bearings aren't either rusted garbage or overtightened you'll be able to do the same with 8" tires.
 

IraRat

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

The ATV changes everything.

My guess is the max weight on that trailer is 800 pounds--forget what tires you put on there. (My similar HF is 800, with 12s.)

Now, subtract your board weight to beef up the bed, and subtract your safety cushion to NOT go to absolute max capacity, and is your ATV light enough to get on there?
 

Bronlonius

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

If your bearings aren't either rusted garbage or overtightened you'll be able to do the same with 8" tires.

Maybe, but on a 2000 mile trip I didn't want to take any chances. Plus I had the added benefit of the trailer having identical tires/spare as the car.
Btw, where do you get 8" tires that have a 70-80mph rating?
 

lrak

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Re: Small Utility trailer 8" to 15" tire upgrade is ok to do?

Maybe, but on a 2000 mile trip I didn't want to take any chances. Plus I had the added benefit of the trailer having identical tires/spare as the car. Btw, where do you get 8" tires that have a 70-80mph rating?

I've done a couple 1000 mile days while pulling the Whaler with 4.8x8 tires back and forth from the northeast to the FL keys. If the bearings don't heat up in the first 20 miles, they aren't going to heat up. 1200rpm is not a big deal for properly adjusted/greased tapered roller bearings.

I agree having an identical spare is nice, but consider the size and weight of an 8" spare. They weigh about 10 lbs. Sticking one on the tongue is no big deal. They are also cheap. Tires for the Whaler trailer are $27 each on etrailer. A spare mounted on a galvanized rim is $44. I can replace ALL three tires for my Whaler for $100. EACH of the five 15" tires under my sailboat is $115.

The ST tire spec says tires are rated for 65mph at their maximum load and pressure. The details of the spec also state the tires must be rated at 75mph at 10PSI above the required pressure for the load. I simply put a 5.7x8 load range D tires with a capacity of 1175lb per tire on my 1200lb rated utility trailer and 4.8x8 load range C tires with a capacity of 760lbs per tire on my 13' Whaler trailer (trailer, boat and motor is about 900lbs). If you look at the load/pressure tables the tires will carry my maximum loads at 10psi below the maximum. So I inflate them to the maximum and look at that spec'd to 75mph!

The other thing about the rating is that it is for sustained speeds. The issue is heat buildup. The tire isn't going to blow up if you are driving along at 70 get behind some slow traffic, speed up to 80mph for half a mile to pass, and move back into the right lane at 70mph.
 
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