Has anyone tried these tubeless? I know supersonic ones are hell to seal, but ordered a race sport race king at the weekend, then annoyingly read the post on MTBR about how despite them being ‘tubeless ready’ they don’t seal that well. Anyone had problems?
Also read that the 2.2 Race King in the race sport comes up smaller than the supersonic one, nooooooooooooooo!Is this true?
Now wondering if I should just send them back, and either stick with tubes and supersonic versions or switch to Schwalbe’s or something else.

Im still trying to seal a set of x-king RS (and they are marketed as being UST ready). The sidewalls is the issue, loads of pinholes. I’ve got one sealed up now while the other is losing around 5psi overnight. They were also one of the more difficult tyres to initially seal (started the process last Friday)

Since starting I’ve read the key is to buff up the inside of the tyre to lessen then waxy compound, but also to provide a surface for the sealant to key onto. Also I started with Joes sealant, and got no where, so tried Stans and have had much better results.

Also read that brushing a layer of latex and glitter on before you start will speed up the process (cant vouch for that just yet).

So far I’ve got as far as putting about 300 mls of stains in each wheel, and leaving it flat on its side, this seems to be working (the bathtub bubbles have slowed to a trickle now).

Worth persevering though as the tyres weighed in at 475 and 486 gms respectively which is a significant saving over the 830 gm Panaracer Fire X Pro’s they are replacing.

Mounted to a set of X819 / with hopes they weigh 1670 gms front and 2015 gms rear with approx 50 mls sealant in each.

I’ve a set of Supersonic Racekings fitted to a Hope Hoops Crest wheelset, by comparison the front is 1430 gms (with inner tube), but they are ridiculously thin in the sidewall and think they would make the x-kings look easy to seal by comparison.

I have got both race king (supersonic) and X king (race sport) and they can be buggers to seal, last time i swapped them, i brushed some stans sealant around the bead which helped.

had the same as you mightymarmite with the x kings, when i fitted them the sidewalls looked they had been shot, there were so many pin holes, so i just put in more sealant, now running 4 ounces in each wheel and been ok.

A customer insisted we do them and it was a joke – pouring out the sidewalls on one and not much better for the other. Had to put so much sealant in that he may as well have run proper UST tyres (he was trying to save weight!!).

I’ve got speed king supersonics, tried going tubeless with them and it didn’t work for me. couldn’t get it to seal all round and when I put water on the tyre, air was visibly foaming/mousing thru the side walls. I gave up quite quickly and I should point out that I hadn’t tried going tubeless before. Someone on here did claim to have succeeded, but he said it took him weeks or months to stop air coming thru the side walls. I’ve gone back to running them with supersonic innertubes.

I’ve got the X King RS and they were a bugger to seal – as others have said, the sidewalls are the issue. I had to add extra sealant (90-100ml) and then pump them up, spin, pump them up, spin, etc, numerous times over the best part of a week. If you can be bothered to persevere, they do eventually seal.

Conti are obviously aware of the issue. If you go to Conti’s website and look at the description of Race Sport, the blurb now says:
Perfectly fine with a conventional tube, but when carefully installed by a professional mechanic or seasoned tubeless-ready user, Race Sport can also be used with a variety of liquid sealants in a tubeless setup.

Careful attention to mounting instructions, a sealing period of several days, and variable amounts of sealant depending on type used and specific riding conditions, may be required to achieve reliable tubeless-ready performance.

RATS! Looks like I’ll just send them back when they come, I am not sure I can really be bother spending ages sealing them, especially if the race king Racesport is not as big as the supersonic version. Oh well, thanks for the advice…will have to try another make for tubeless.
Thanks

So far I’ve got as far as putting about 300 mls of stains in each wheel, and leaving it flat on its side, this seems to be working (the bathtub bubbles have slowed to a trickle now).

300ml of sealant?! That’s 300g, you may as well run DH tubes!

Schwalbe FTW, Rons or Ralphs are lighter, and convert really easily. Ive heard bad things about the durability of the Conti’s once you’ve got them to seal.

I always start with excess fluid so when laid flat a decent covering will go around the entire circumference. Once side walls are sealed break bead and draw out excess with the stans applicator syringe. Works (mostly) for me.

I fell for the whole tubeless ready too. The x-king race sport I bought has yet to properly seal after 3 weeks on the bike, and has already got two pinholes. I have a new 2011 NN UST ready, it will be going on soon I think.

Oli B recently did a video talking about how to fit tubeless Contis
it might help:
Oli B Fitting Conti Tyres

The tires he was fitting aint the race sport versions, that’s for sure.

Where’s the bit where u drop the wheel, spilling stans all over the kitchen floor (and dog), then spend 40 minutes cussing and cursing when the buggar bead wont seal, sweating like a demented ape while you crash up and down on the track pump. Wonder if he will mount mine next time?

That video with Oli Beckingsale, if you go to 3:55 you can clearly see that it is, indeed, the Race Sport version.

I’ve just recently had the X-King 2.2 Race Sport tyres installed on my ZTR Crest rims. I was pleasantly surprised; the sidewalls were not quite as porous as the Rubber Queens 2.2 folding non-UST (with Black Chili) which I got installed on my old bike. It took only a few of Stan’s “shake the wheel and rest” method for each X-King RS tyre to seal to an extend that I could no longer see the bubbles. That was on Friday. I’ve still got to do some decent riding on them but so far they seem fine.

You just need to spend a little bit of time on them. I put some Stans fluid into them and scrubbed it round the inside of the tyre and the bead, then pumped them up. I then put in a small bottle of Stan’s and re inflated them gave them a good shake all round and they are still up after a week in Wales.
I have been running Mountain King 2 protections tubeless on my other bike for weeks after following the same process, it takes maybe 10-15 minutes per tyre.