changing 8" tires to 13" tires.

[dockrat100]

Re: changing 8" tires to 13" tires.

Fenders are coming, trying to get this done one step at a time. Bunks will be extended shortly.

 

[limitout]

Re: changing 8" tires to 13" tires.

Fenders are coming, trying to get this done one step at a time. Bunks will be extended shortly.

ok, switching from 8" to 12" tires will give you about a 2" lift and flipping the axle will give you about another 3" of lift so by doing both, that's roughly 5" of lift right there. having the axle under the springs gives you more fender clearance as well so it solves any clearance issues you might have with the 13" tires.

the difference in 12" to 13" is nothing height wise because its a wider tire so it rides softer but will have more "squat to it so overall height will be about the same as a 12" tire but the big difference will be in how wide the tire is which is almost double the width of a 12" tire. all this is to explain 12" is all you need but 13" is just a matter of personal preference and it gives you a smoother ride. plus in your case you have access to better prices.

I wouldn't extend the bunks, they shouldn't be any more then 3-4" past the last bracket and the transom of the boat should be sitting on the bunks and not extending past them so the whole boat needs to move about 12-18" forward onto the trailer more. if you don't have room for that then look into adding onto the tongue or just getting a bigger trailer is what you need to do.

it doesn't look too small for the boat but before you spend money on it lets see some pictures showing the entire boat and trailer tongue to motor and how it fits on that trailer. step 1 is getting the boat sitting correctly on the trailer.

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

the one thing I see missing here is THE MOST IMPORTANT consideration when matching tires to trailers... the combined load capacity of the tires should be as near as possible to the weight they will carry... good luck finding such large tires that are appropriate to the weight of that boat.

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

Also looking at the pictures... that trailer is ridiculous with the big wheels...Looks like a 6 yr old kid wearing daddy's boots... Go back to 8" wheels and move that boat WAY forward on the trailer OR find a longer trailer.... Extending the bunks will do absolutely nothing for you.. the longer bunks will simply flex downward and will not support the boat.

find a way to secure the motor in the up position... transom saver, ratchet strap... or take it off and lay it in the boat

Keep the trailer LOW..... raising it makes it worse for launching and retrieving a boat... You are trying to fix a non existent problem...


If this sounds like I'm down on you I promise that isn't the case..... just not gonna sugarcoat anything..... wish ya the best of luck w ur project

EDIT:... for those that worry about 8" wheels on the highway, I have towed over 1000 miles one way with cruise set on 78 mph stopping only for gas and bathroom or lunch breaks MANY times on 8" trailer wheels with no problem whatsoever or even any excessive heat in a bearing.... They are designed for highway service and are more than up to it.

A taller tire, while it turns slower, will also put more side load on the bearing in curves and off camber conditions such as crowned roads.

 

[steelespike]

Re: changing 8" tires to 13" tires.

Looks good to me.The only draw back to the height is if you have any shallow launches.
Thats a nice style aluminum boat has that real boat look from the 30s,40ss and 50s.

 

[steelespike]

Re: changing 8" tires to 13" tires.

Boy what a turn around now we're telling him its too much tire.
I do feel a 12" tire would be a better match and at $56 dollars for tire and rim
with heavy duty resistant paint and nice pin stripe.
I don't understand matching tires to the weight of a "lightweight" boat.
Simply adjust the pressure to match the weight.
I had a brute of a single axle trailer with 15" split rims with 800X15 tires.
It was so beefy you could jump up and down on the fenders, I'm 220 lbs.
I didn't tow a lot of times But up to about 300 miles some times.
Boats from a 15ft aluminum outboard to a 23ft Long deck antique launch.
Also a 15 ft vintage vintage inboard,22 ft Hutchinson inboard,a 18 ft hardtop Lyman
inboard All vintage wood boats.
While I agree he may need to move the boat forward to get a better balance
The bunks aren't going to flex with the weight of that boat motor combination.
What's the total weight 500 lbs.?

 

[limitout]

Re: changing 8" tires to 13" tires.

I don't understand matching tires to the weight of a "lightweight" boat.
Simply adjust the pressure to match the weight.

got to agree, I can see where it might be bouncy in the right conditions if you have big tires with a small trailer and no weight load on it but simply adjusting air pressure properly for the load is all that is required because I don't think he is planning to be going out and jumping railroad tracks with it lol.

 

[lrak]

Re: changing 8" tires to 13" tires.

As someone who owns trailers with 8", 12", and 14" trailer tires, I'd switch it back to 8" tires pretty quickly if I bought it off you. Less rotating mass makes braking easier. Less un-sprung mass makes for a smoother ride. Logically I don't think 1200rpm is a big deal on properly greased and adjusted tapered roller bearings. Practically I've personally done over 1000 mile days with 8" tires and at least 800 of that over 65mph.

What prompted you to switch tires instead of just raising the bunks a couple inches?

 

[MH Hawker]

Re: changing 8" tires to 13" tires.

Put a set of 32 inch super swappers on it.

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

the REASON for matching tires to the load is because trailer tires are specified to run at only one pressure... "adjusting pressure" is haphazard at best..... lower pressure than specified increases heat and heat is what kills tires

beyond that there is absolutely NO GAIN for the O/P in running these bigger tires.... He doesn't need more clearance.


As for the flex debate... those 2x4's will flex with 20 lbs on them.... in fact while it would be a VERY small amount the will likely flex slightly even under their own weight... Why does such a small amount matter? because of work hardening of the aluminum which in turn also gets flexed with every bump in the road. Work hardening leads to cracking......

In the end, the boat will most likely last a long time even being poorly supported BUT as I said before the extra long bunks are NOT supporting anything... don't believe me? go stuff your fingers between the hull and the tip of the bunk.... the boat will still be touching up by the trailer frame but amazingly your fingers will not be crushed.... or simply grab the bunk and pull down on it... then observe the light between it and the hull....

IF by some chance this fails to convince you then try a string line along the hull next to the bunk... if you do have good pressure against the bunk way out back then you have a hull that is flexed to meet the bunk

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

got to agree, I can see where it might be bouncy in the right conditions if you have big tires with a small trailer and no weight load on it but simply adjusting air pressure properly for the load is all that is required because I don't think he is planning to be going out and jumping railroad tracks with it lol.

I challenge you to find ANY manufacturer of trailer tires that advises running at ANY pressure other than the rated pressure on the sidewall.

Hint... none do.

 

[dockrat100]

Re: changing 8" tires to 13" tires.

I agree that tires should be run at recommended pressure.

I do not follow the logic that says you should not run a tire with less than its recommended capacity. I drive semis. What bad will happen to my bobtail rig with no trailer, vs pulling it fully loaded at 80,000 lbs? Nothing. I know we are talking about a larger vehicle, but the principle should hold true on a larger scale. (Should I start adjusting my air pressure when I am loaded vs empty? 45,000 difference there....)

I agree that the boat seems to sit higher than I would like. I may sell the wheels I have and look at replacing them with 12 in tires. But I will launch the boat first and see if it is a pain. I use the boat to hunt in the delta, and generally launch at one ramp. If it launches there, I am a happy guy. If it is a pain to launch, I can pick up the boat and toss it in the water without much strain.

I agree that the bunks are way longer than they need to be, and much of it is not supporting anything in the front. Moving the boat forward much is not possible, nor is extending the tongue practical. I may run a piece of angle iron from the rear of the bunk down to the trailer frame to eliminate any flex that may exist in the 2x4 bunk.

 

[dockrat100]

Re: changing 8" tires to 13" tires.

BTW- Steelspike, where do you get the 12 inch tires for $56? That is much cheaper than I get them for around here...pm me if necessary.

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

I agree that tires should be run at recommended pressure.

I do not follow the logic that says you should not run a tire with less than its recommended capacity. I drive semis. What bad will happen to my bobtail rig with no trailer, vs pulling it fully loaded at 80,000 lbs? Nothing. I know we are talking about a larger vehicle, but the principle should hold true on a larger scale. (Should I start adjusting my air pressure when I am loaded vs empty? 45,000 difference there....)

I agree that the boat seems to sit higher than I would like. I may sell the wheels I have and look at replacing them with 12 in tires. But I will launch the boat first and see if it is a pain. I use the boat to hunt in the delta, and generally launch at one ramp. If it launches there, I am a happy guy. If it is a pain to launch, I can pick up the boat and toss it in the water without much strain.

I agree that the bunks are way longer than they need to be, and much of it is not supporting anything in the front. Moving the boat forward much is not possible, nor is extending the tongue practical. I may run a piece of angle iron from the rear of the bunk down to the trailer frame to eliminate any flex that may exist in the 2x4 bunk.

"what bad will happen" = crappy ride... if you are in an air ride truck then much of that will be masked but try it in the old all spring 4 axle mack R model I used to haul heavy equipment with and you would BEG for a back haul just to avoid running empty...

The hard over rated tires will beat the snot out of your boat compared to a lighter tire on which the sidewall can deflect to take the jolt out of a bump.

other than that tho nothing bad happens

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

BTW- Steelspike, where do you get the 12 inch tires for $56? That is much cheaper than I get them for around here...pm me if necessary.

https://www.google.com/search?q=12+...+tire&rls=org.mozilla:en-US:official&tbm=shop

 

[steelespike]

Re: changing 8" tires to 13" tires.

BTW- Steelspike, where do you get the 12 inch tires for $56? That is much cheaper than I get them for around here...pm me if necessary.

I looked up Walmart on the net. $55.95 wheel and tire. I'm assuming the same in store.
And these are about 100 times better than the Harbor freight tires mentioned below.
Some years ago I bought rims and tires from Harbor freight. At the time I think about $30.
They worked ok on my electric car but I wouldn't recommend them.
As far as tire pressures go I think we're dealing with a really light load probably 1/2 of the tires rating.
Running at a pressure to match that load surely isn't going to cause tire fatigue.
Unless he's smuggling bowling balls in the boat that whole outfit trailer and all has to be under 1000 lbs.
I just sold my VW bug the recommended tire pressure on the front tires is 18 lbs. That is surely below that recommended
on the tire.That pressure matches that required at the front of the car.

 

[Home Cookin']

Re: changing 8" tires to 13" tires.

why does it matter what the trailer looks like? It's an old trailer with an old boat. He got his height and better ride. Prop the motor up with a dowel or 2x2 horizontal under the motor.

I think what looks funny is the wheels all the way back, almost like the trailer was cut off (salt water trailers can loose their last 3 feet).

Don't overthink--and overspend--it. For a boat that weighs practically nothing with a light motor, nothing really matters.

 

[kfa4303]

Re: changing 8" tires to 13" tires.

I actually prefer smaller tires myself. They make getting the boat into/out of shallow water much easier, especially when combined with a float-on trailer. When used together, they will often allow you to launch and retrieve the boat without even submerging the hubs, which is nice here near the coast where saltwater eats trailers and wheels. While it may be overkill in areas with lots of boat ramps and/or freshwater, riding nice and is awfully handy where folk like to get into skinny, salty water where launches are often non-existent. The pic in my signature is one such place. I have to use my magic tilt trailer just to get in and out as the water is only about 12" deep at the most.

 

[naturelover]

Re: changing 8" tires to 13" tires.

So, not to derail, but brings up a question....

My little 8" tires are supposed to be inflated to 60psi, and at that pressure, I don't think they have any give with my 12' aluminum boat.

Been thinking of dropping them to 30 or so.

I run 8"ers on my boat trailer and my 4x8 trailer. They seem fine for the boat trailer, but I wouldn't run them without bearing buddies on the 4x8 trailer.

 

[smokeonthewater]

Re: changing 8" tires to 13" tires.

And by " not to derail", what you really mean is "THIS IS A HIJACKING!" lol

they have more "give" than you think... they aren't meant to deflect much... just enough to lessen the impact of a hard hit such as a pot hole enough to prevent damage.

you can do as you choose... the tire manufacturers and I recommend running at the rated pressure