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The mkiv Supra Owners Club

Inner tubes - are they safe, and are they road legal?


jim
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I'm hoping someone that uses inner tubes (I know a few do for racing still) might be able to give me some advice please. :)

 

I've a set of split rims that have been breaking my heart for a long time now. They've been split and rebuilt three times and I can't get two of them to hold air. I've a guy looking at them again for me this week to see if they'll hold with a different type of sealant and if it doesn't work this time I'm about ready to chuck them in the bin.

 

As a last resort, I was thinking of trying an inner tube in them but I've no idea if it's road legal, or if you can get them for the tyre sizes that I've got. The tyres are 225/40 (9.5" rim) and 245/40 (10" rim). Anyone know if it's possible to get tubes in these sizes and if it's safe (or legal) to use them on the road?

 

Thanks!

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According to just tyres website .

Tubes in Tubeless Tyre

 

Inner-tubes of the correct size can be used with tubeless tyres if they are correctly fitted.

 

Please remember that by fitting tubes in tubeless tyres, in the event of a puncture, the assembly will behave exactly like a tubed tyre – it is likely to lose pressure more rapidly than a tubeless tyre assembly. Where tubes for certain low profile tubeless tyres are not available, an alternative size tube should NOT be fitted

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Under duress a tubed "tubeless" tyre will run a lot hotter than if it was run as intended, without a tube. Sealing a split rim isn't rocket science, I do loads, what sealant are you using? What are the centres like, cast? You could *PROBABLY* have them machined for O rings and not have to mess with sealant at all.

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Lol, not the green/orange/pink ones Carlo :D

I'm not sure what type of sealant the guy used chris (they were done by a refurbisher) but apparently it was proper stuff. I asked about welding them but they said that the basket was magnesium alloy and the lip and face were a different alloy, and welding couldn't be done (by them anyway).

Can I ask exactly what you mean by machining for o rings please chris? I'd been thinking that there must be some way of even bonding a thick rubber strip around where the two sections meet and melting the edges to make it air tight, or something used in boat building that might work.

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Loctite 5699 is what I normally use. I have also used the stuff Compomotive apparently recommend, which is Dow Corning 794F sealant.

 

Rim halves need to be burr free, and wire brushed on the sealing flanges, then cleaned with brake cleaner and allowed to dry. Similarly the centre section. Observe correct bolt torques (probably a lot less than you think).

 

Run a bead of sealant around the cleaned inner V of the built up wheel sections and wipe into a neat, smooth edged bead with a finger wetted in soapy water.

 

I'd need a decent photo of the dismantled centre section to tell if there's enough room for an O ring groove and the bolt holes.

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