Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

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Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Mucky » December 28th, 2018, 8:54 pm

Hey everyone,
I am having a *beep* of a time trying to set up my Jumbo Jim 4.8 tire on my 80mm carbon rim. I can get the tire on fairly easy, into the center channel. The problem is trying to get some kind of seal so I can start to pump it up. I can't seem to get the bead of the tire to stay out of the channel and near the edge of the rim. As of now, I have a tube in the tire, at 13 psi, and will let it sit overnight. My plan is to pop one side off and keep the other seated and try and go from there.

I will add that I got a 26" tube to put around the outside of the tire while trying to mount it. I saw it on youtube. Supposed to help keep the tire from kinda folding over and help keep the bead seated. We will see, but first I have to get the bead somewhat seated

If anyone has succeeded with a carbon rim(Chinese or not) and this tire, or any fat tire really, please help me out.

Thanks
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby c0nsumer » December 28th, 2018, 11:59 pm

Are you using an air compressor?
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Mucky » December 29th, 2018, 12:06 am

Yes I am.
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby c0nsumer » December 29th, 2018, 8:53 am

I've had no issues with JJs on my HED BAD rims, personally.

I'd do the pre-seat with tube thing you're doing, then if needed throw a band strap around it to push the loose bead out towards the rim. Start inflating, then release the strap as it seats and begins inflating. I've had to do that on non-HED rims (carbon and aluminum) once in a while and it always works. Just takes a little finesse.

(I can see how it could be done with a tube too...)
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Mucky » December 29th, 2018, 2:36 pm

Thanks for the help Steve.
When you take the tube out, how do you get that side of the bead to create enough of a seal? With the strap? I've seen a couple different techniques on the interweb, (trying to pull sidewall of tire out,or firmly pressing tire downward while the wheel is vertical) but these tires are way to tight to have them be successful.
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby jthomp » December 29th, 2018, 2:52 pm

What did you lube the bead with?
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby c0nsumer » December 29th, 2018, 3:05 pm

Mucky wrote:Thanks for the help Steve.
When you take the tube out, how do you get that side of the bead to create enough of a seal? With the strap? I've seen a couple different techniques on the interweb, (trying to pull sidewall of tire out,or firmly pressing tire downward while the wheel is vertical) but these tires are way to tight to have them be successful.


I just pull that side of the bead over a bit with my hand and dump air in.

Are you removing the valve core?
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby barrybs » December 29th, 2018, 7:28 pm

Remove the valve core and use a rubber tipped blow gun to initially seat the bead. You want high volume !
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Steve_Balogh » December 29th, 2018, 8:50 pm

One thing I don’t like is how some tires come with rubber bands on them which put kinks into the tire. One way to prevent this from making inflating issues is to first put an inner tube in the fresh tire without the rim and pump it up and leave it sit for a day or two. Makes installation a little easier. I use a flash pump. I use JJ 4.8 on Nexties 90mm rims.
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby bender16v » December 29th, 2018, 9:27 pm

I had a devil of a time with a 3.8" Hodag on an 80mm rim. In the end what worked was inflating with a tube inside to seat both beads, then breaking one bead to remove the tube, then hitting it with as much air as possible. I kept the tire lubed with soapy water and removed the valve core and I ended up making this device with a push button valve and an 8mm (5/16") piece of tubing that slides over the valve stem. The blow gun method that barrybs mentioned above would accomplish the same thing. I have some 4.8" JJs sitting around but I'm not going tubeless on my 26" wheels.

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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Mucky » December 29th, 2018, 9:48 pm

I use soapy water to lube.

I have not removed the valve, but will try with the core removed.

I too hate that the tire comes with rubber bands on them. I will try the tube in tire trick.

Thanks for all the help. I will report back
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby Mucky » December 29th, 2018, 10:10 pm

Well, I got it on. I went on pretty easy, with one good boom. Took about 9psi. The tube 1st method is definitely the way to go. With the one side of the bead seated, I could create enough of a seal with just pushing on the tire with my hands. Knowing that, I had a good feeling. I didn't need to remove the valve cor. I use a prestaflator. Cranked up the air compressor to 100 psi and let her rip. I have no sealant in yet with no apparent leaks. Yes I am going to put orange seal in.

On a funny note,
when I was releasing the air from the tube, it was creating a vacuum and sucked the tire in. These tires are super tight and make a great seal.

Thank you all for your help and ideas. I hope other people can find this and it helps them.

Thanks again
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby c0nsumer » December 30th, 2018, 9:54 am

Ohh, yeah. If you weren't removing the core before, that was probably the main problem. That radically restricts airflow.
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Re: Need Help - Jumbo Jim 4.8 on 80mm Carbon rim tubless

Postby flamingo » December 31st, 2018, 10:00 pm

Late to the discussion. Luckily my 4.8 JJ opened up and sealed the bead upon the first blow. However I had the same problem few times on regular 2.2 tires. I would remove the valve core and insert a tube into the wheel so that I would have two free hands while blowing the air into the tire. As I opened the valve I would move the tire's bead outside towards the rim. Once it took a while. I emptied 15 gal air compressor.
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