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Nitrousbird

I want to convert my trailer from 14" wheels to 18"

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Nitrousbird

Trailer is a 2001 SMP. Has 14" rims currently.

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Has disc brakes on both axles (replaced by previous owner), and bearing buddies, all done last fall.

I don't want to dump a fortune into the conversion. I am partly justifying it because I need desperately need 2 new tires for my 18' car hauler, and all 4 rims on it suck. I would be able to use these rims/tires on it offsetting some of the cost.

I figure the lug pattern is 5x4.5" I have 4 17x9.5" Konig Flights that would fit (drilled for 4.5 and 4.75) but are obviously way too wide.

- What width will fit under the stock fenders? Or am I stuck upgrading to wider fenders?

- What is the proper offset?

- I also question what wheels will fit over the center hubs, as they stick out a decent ways with the bearing buddies. Or am I stuck running an open hub wheel?

- Tire size suggestions?

I'm willing to go 17" rims as well - nothing smaller than that though.

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Soon2BV

Here are some things to consider -

Measure your tires and the ones you want to add. Determine if they will fit under the fenders (height) or if you need to raise them.

Measure the width of the tires and wheels. Will you have clearance at the inside (what is the depth of the wheel hub from the rear and how much room between the trailer frame and the hib) and will you have clearance at the outside at the fender?

Next is, how much do you tow? You will have a hard time (impossible?) finding trailer tires bigger than 15". Trailer tires are made to be twisted and loaded in a way that vehicle tires are not. Regular vehicle tires don't have the sidewalls that trailer tires have. (Have someone pull you boat slowly around a corner and watch the tires.) If you tow a long way and often, the new tires may not hold up to the loading.

Next, the larger tires will be taller, so your trailer and boat will sit higher. Do you have clearance to get into your storage location? Would an extra few inches eliminate any clearance?

Not trying to kill the project, just offering things to consider before you jump in.

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MaddMaxx

Here are some things to consider -

Measure your tires and the ones you want to add. Determine if they will fit under the fenders (height) or if you need to raise them.

Measure the width of the tires and wheels. Will you have clearance at the inside (what is the depth of the wheel hub from the rear and how much room between the trailer frame and the hib) and will you have clearance at the outside at the fender?

Next is, how much do you tow? You will have a hard time (impossible?) finding trailer tires bigger than 15". Trailer tires are made to be twisted and loaded in a way that vehicle tires are not. Regular vehicle tires don't have the sidewalls that trailer tires have. (Have someone pull you boat slowly around a corner and watch the tires.) If you tow a long way and often, the new tires may not hold up to the loading.

Next, the larger tires will be taller, so your trailer and boat will sit higher. Do you have clearance to get into your storage location? Would an extra few inches eliminate any clearance?

Not trying to kill the project, just offering things to consider before you jump in.

Add in does the taller tires change the pitch of the trailer at the hitch and, if so, does the hitch have to be changed. Also, with taller tires/trailer, the deeper you will have to go in the water to launch/retrieve the boat.

Edited by MaddMaxx

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SmoothWaterMan

I added this reply back in 2007 on themalibucrew for another poster. The main difference between then and now is most everyone skips the 16's and jumps to the 18's. Same formula works, and you'll need new fenders.

A tandem will run 14" stock. (205-75-14 typical) I believe the pattern is 5 on 4.5.

When we up the wheel size we jump to 16". They fit really nice, although we do typically go to a wider 10" fender for more of a CA look.

There are trailers out there with 18' and 20" wheels on them - I think there are some posted in this forum over the years of TA's and Triple Boatmates with dubs on them.

As a point of reference:

Tire size formula: "add 10, subtract 10, add 1" for sizing tires

to match the original rolling size when you add larger wheels.

For instance, (and maybe you know all this),

We use 205/75-14 tires.

If we go to a 16" wheel, then we need to run the formula twice, which gives

us a new tire size of 225/55-16.

Peter

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SmoothWaterMan

Added note :

The +10/-10/+1 is a very general rule, mainly for sub 18" sizes. (I believe up to 16" it's perfect)

205/75R14 to an 18 would be 205+40/75-40/14+4 = 245/35R18

That doesn't work out exactly correct because the 14" would have a diameter of approximately 26" and the 18" diameter would be approximately 24.75" whereas a 255/40R18 would result in a diameter very close to 26".

Source Credit : Boatmate Trailers

Peter

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nyryan2001

Also its been well documented that throwing bigger diamter tires/rims onto a vehicle or trailer with brakes... without upgrading those brakes.... puts those brakes at a mechical disadvantage and your stopping power is reduced. Think of it like a breaker bar over a rachet....except in this case, the road is the breaker bar because you put a bigger rim/tire combo on there. The larger diamter puts the brakes at a mechanical disadvantage. I think there are claculators that will show you how the forces increase by a 1" increase in diamter...

See if you can do it up to 18" rims keeping it the overall same diamater or very very close. Not sure how you would upgrade our hydraulic fed brakes. Everytime I see vehicles where folks just throw on larger diameter rims/tires without upgrading the brakes, i think DUMMY.

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Bill_AirJunky

I bought my boat & trailer with Pirelli Pzero Nero M+S 235x45x17s on it.

Yep, their sports car tires. Rated W for 168 mph & over 1200 lbs per tire. :crazy:

The conversion was done by the original owner, a guy from pdxwake.com..... a group of Portland area riders. There are quite a few of them who have done this to their trailers. Apparently their not having much problem with them either. I think the fenders are totally stock. The tires are really not any taller than stock, but may be a bit wider.

I originally expected that I'd be converting the trailer back to steel wheels & conventional trailer tires. But after no problems in nearly 4 yrs & probably about 2000+ miles / year, and seeing how many problems other guys have had with their trailer tires...... I'll probably keep'em. :crazy:

IMG_2020Large.jpg

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Malibuzer

Also its been well documented that throwing bigger diamter tires/rims onto a vehicle or trailer with brakes... without upgrading those brakes.... puts those brakes at a mechical disadvantage and your stopping power is reduced. Think of it like a breaker bar over a rachet....except in this case, the road is the breaker bar because you put a bigger rim/tire combo on there. The larger diamter puts the brakes at a mechanical disadvantage. I think there are claculators that will show you how the forces increase by a 1" increase in diamter...

See if you can do it up to 18" rims keeping it the overall same diamater or very very close. Not sure how you would upgrade our hydraulic fed brakes. Everytime I see vehicles where folks just throw on larger diameter rims/tires without upgrading the brakes, i think DUMMY.

My Extreme trailer came with 20" tires and rims. I checked the brake calipers on it verus another trailer with just 15" tires and they run the same part number. I knwo what you are saying but I do know that the brakes on this trailer work very well. :whistle:

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vette-ski

My Extreme trailer came with 20" tires and rims. I checked the brake calipers on it verus another trailer with just 15" tires and they run the same part number. I knwo what you are saying but I do know that the brakes on this trailer work very well. :whistle:

As long as you go with a lower aspect ratio tire (shorter sidewall given same width) and keep the overall outer diameter of the tire close to the stock 15" tire (26.1" diameter), braking shouldn't be affected at all.

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pielet97

As long as you go with a lower aspect ratio tire (shorter sidewall given same width) and keep the overall outer diameter of the tire close to the stock 15" tire (26.1" diameter), braking shouldn't be affected at all.

Correct. The brakes will have no idea the tire is different as long as the diameter is the same, unless the originals had a tendency to lock up, then the new tires would actually stop better.

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DONTW8

Here is the Old Man Party Pooper answer.

Bills wheels look great. But..............

I would look to add weight capacity to each tire.

Specifically by going up a load rating in tires.

If you have C rated a D is better and an E rating is better than that.

I raised my trailer fenders by 1 - 1 / 2" and went up a wheel size.

There are more choices in high load capacity tires in the 16 inch and 17 inch sizes.

Tire Rack can be your friend for getting the height and diameter of tires.

Because there are so many small SUV's out there it is easy to find a wheel that fits a Honda CRV or similar that is 16 or 17 inch.

From there you can mount a Load Range E tire that will totally eliminate any worries about blowouts due to overhating.

You can run trailer tires at 80 PSI in an E rating. Who cares if it rides rough ?

Example 265 / 75 R 16 tire load E is 3408 # load rating.

a 225 / 75 R 16 load range E is 2680 # rating. It is only a 29.3" diameter.

Do this and you won't need a spare.

Edited by DONTW8

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nyryan2001

Ya sam here. I like the rims and tires, but at 1200lb capacity i'd pop them.

My boat is 6500-6800lbs with the trailer depending on gas level. Perhaps 800-1000lbs of that is distributed to the truck via tongue weight...

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Bill_AirJunky

Ya sam here. I like the rims and tires, but at 1200lb capacity i'd pop them.

My boat is 6500-6800lbs with the trailer depending on gas level. Perhaps 800-1000lbs of that is distributed to the truck via tongue weight...

I hear that, especially with any of the bigger boats some of you guys have. I hope your talking about a Malibu & not that little 205 in your profile. BTW, not sure where you got that pic..... but the guy who built that trampoline tower was living south of you near Houston.

My little Vride tops out at maybe 4200 lbs unloaded. So even fully loaded I think I'm still within the range of these tires. Frankly I didn't think they would last as long as they have so far. But after seeing the problems some of you guys have had with "trailer tires" from Carlisle & Goodyear, I'll probably keep using these, maybe bump up in capacity.

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Nitrousbird

Stock Tires are 205/75/14 = 26.1"

Closest 18" tire sold is 225/45/18 = 25.97" It is .78" wider though

Closest 17" tire sold is 205/55/17 = 25.87"

I don't think tire size is the worry (and you would never notice going from 25.87 to 26.1). But making sure to have the proper offset / wheel width for the tire is. I'm not worried about the brakes - 4 wheel discs all around, stops very well - far better than my last boat.

How much does a new set of wider fenders run, and from who? If so, what would be a suggested tire width for that?

Load wise, Malibu says the boat weight 2900. Hard to say for sure, as I'm sure it is option dependant, but I'm sure the additional weight of tower/wedge/etc. is offest by the lighter LS1, so I'm sure it is close to that number. But let's say 3000lbs. Trailer is 1240lbs. Most of the passenger tires I'm seeing are rated around 1500lbs = 6000lb rating total. I'll never get anywhere near that, even fully loaded with gear towing. I also have heard from those with trailers that came with larger diameter rims from the factory all seem to be running passenger car tires, so I'm not concerned at all about that. 90% of the time, I'm towing 4 minutes to/from the boat ramp at 45MPH or less. I will occassionally tow 12 minutes to a different lake (50 MPH or less), and maybe twice a year we will go somewhere 1+ hours (haven't done over an hour in a few years, but plan to go 6-8 hours away next summer).

I bought my boat & trailer with Pirelli Pzero Nero M+S

The conversion was done by the original owner, a guy from pdxwake.com..... a group of Portland area riders. There are quite a few of them who have done this to their trailers. Apparently their not having much problem with them either. I think the fenders are totally stock. The tires are really not any taller than stock, but may be a bit wider.

I originally expected that I'd be converting the trailer back to steel wheels & conventional trailer tires. But after no problems in nearly 4 yrs & probably about 2000+ miles / year, and seeing how many problems other guys have had with their trailer tires...... I'll probably keep'em. :crazy:

IMG_2020Large.jpg

I like those wheels. Brand/offset/width/diameter of wheel.

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CumminsBu

Look into Toyo proxies 2 tires, they have some of the higher load range I have spec out for 17" and 18"

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Bill_AirJunky

I like those wheels. Brand/offset/width/diameter of wheel.

Wish I could tell you what brand they are. No caps & no logos I've ever seen. Pretty sure he bought them at Les Schwab though.

I might be able to get a tape measure on them to tell you the offest though.

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Sliderfiii

interesting thread...I am no tire expert but from what I understand it is not legal here in Ontario to use automitive tires on a trailer....might want to check into that.

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wdr

I have factory installed passenger car tires on my '10 DA, BM trailer. NEXXUM (Korean company) 255/45/ZR18, why they went to the expense of putting on Z rated tires is beyond me. They do say Extra load and are advertised as such online, but are only a 2 ply sidewall and rated at @ 1950 lbs per tire at max inflation. This rating barely covers the weight of the boat (3900 Malibu figure) and not the trailer wt + fuel + gear. To date, they tow and track great and don't show undue wear or heating when towing And I haven't noticed any unusual wall flex when cornering even on my 1900 mile delivery trip. The down side is I don't even want to know what it is going to cost me to replace these things in a few more years!

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vette-ski

I have factory installed passenger car tires on my '10 DA, BM trailer. NEXXUM (Korean company) 255/45/ZR18, why they went to the expense of putting on Z rated tires is beyond me. They do say Extra load and are advertised as such online, but are only a 2 ply sidewall and rated at @ 1950 lbs per tire at max inflation. This rating barely covers the weight of the boat (3900 Malibu figure) and not the trailer wt + fuel + gear. To date, they tow and track great and don't show undue wear or heating when towing And I haven't noticed any unusual wall flex when cornering even on my 1900 mile delivery trip. The down side is I don't even want to know what it is going to cost me to replace these things in a few more years!

It's a dual axle? 4 tires? That's 7,800 pounds load rating for the tires, plus tongue weight to the vehicle. Or am I missing something? A higher speed rated tire might do better with heat issues.

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LS-One

I'll leave the technical aspects of changing out the tires and wheels to those much more knowledgeable than I. Having had a pimped out trailer on my last boat, the only thing I gained was much more worry if the trailer would be in the same condition as I left it on the launch ramp when I returned from a weekend on the lake.

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Bill_AirJunky

I'll leave the technical aspects of changing out the tires and wheels to those much more knowledgeable than I. Having had a pimped out trailer on my last boat, the only thing I gained was much more worry if the trailer would be in the same condition as I left it on the launch ramp when I returned from a weekend on the lake.

Another one of the little perks of living where you do. Most of the places we go we could leave the doors unlocked & not have any problems.

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Vettesetter

Iv'e seen some aftermarket car rims on trailers, are they using 0 offset, or do they have spacers to correct the offset. For example, if you put corvette wheels on you would need 54mm of spacers to make them 0 offset, can you do that? This is a topic that I've researched and are having a hard time figuring out. I went to a trailer wheel site and they have a few trailer wheels but not what I want.

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jkendallmsce

Another one of the little perks of living where you do. Most of the places we go we could leave the doors unlocked & not have any problems.

Folks do take a liking to shiney things. And when there is no one around the keep on eye one your stuff. I am surpised more trailer are not simply stolen while the owners are out enkoying the day on the water. A set of nice tires and rims is going to set ya back 2k!!!

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Nitrousbird

Iv'e seen some aftermarket car rims on trailers, are they using 0 offset, or do they have spacers to correct the offset. For example, if you put corvette wheels on you would need 54mm of spacers to make them 0 offset, can you do that? This is a topic that I've researched and are having a hard time figuring out. I went to a trailer wheel site and they have a few trailer wheels but not what I want.

Hopefully you are not looking for Corvette wheels, as they are 5x4.75...otherwise I'd have a few wheels I'd be test fitting right now.

I'd love some 10" fender suggestions - seems there are a lot of them out there. I guess a wheel shop could probably figure out a wheel width for me, assuming 0 offset.

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Malibudude

Folks do take a liking to shiney things. And when there is no one around the keep on eye one your stuff. I am surpised more trailer are not simply stolen while the owners are out enkoying the day on the water. A set of nice tires and rims is going to set ya back 2k!!!

That's why mine rim/tires are chained up to the frame when e are out on public lakes.

Love the Toyo Proxies my trailer hugs the road...

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